ABSTRACT
Three years ago H. F. Moore (“Rep. Porto Rican Isopoda,” in ‘U. S. Fish Comm. Bull.’ for 1900, vol. ii, p. 172, 1901) wrote on the Sphæromidæ : “No attempt is made to furnish a key to the genera, owing to the extreme confusion that exists in this family, and it is doubtful if the following two species are properly assigned generically. The dissimilarity of the sexes has frequently misled authors into placing them in widely separated genera, and, while this has not been done in the present case, the limitations of the genera are so indefinitely established that the author has not been able to satisfy himself of the generic affinities of the species described.” It may be added that Moore, in reality, refers both his species to genera to which they do not belong. But his critical remarks quoted are correct, and convey an idea on the state of things ; other authors have complained in a rather similar way, and the extreme difficulty in arriving at some clearness has probably been felt by every carcinologist who has attempted to name or describe a number of animals belonging to the family Sphæromidæ.
Not being able to decide whether Næsa (Leach) or Dynamene (Leach) ought to be used for the European genus, I applied to my friend the Rev. T. B. B. Stebbing, who is specially versed in such questions. He sent me, most courteously, a very detailed exposition, but as he added that he was working on Sphæromidæ, and his results are to be published, I accept his decision that Dynamene must be preferred, and refer the reader to the proofs to be found in his future paper.
On the following pages some abbreviations are generally used, viz. pip.1, pip.2, pip.6, for first to fifth pairs of pleopods, endp. for endopod, exp. for exopod, urp. for uropods.
Mandibles normal, the cutting process not elongate, its
In a species from Simon’s Bay, at Cape, closely allied to or identical with Sphæroma scabriculum (Hell.), the end of abdomen in the female is as in Exosphæroma, -while in the male a notch, as in the male Uynamenella (compare the diagnosis below) is observed; the specimen described by Heller is evidently a male. The female of the species seen by me cannot be separated from Exosphæroma, while the structure in the male alluded to is very curious. For various reasons I omit this form from the conspectus, hoping to obtain more material of allied species.
The genera Exosphæroma, Isocladus, and Zuzara (with Cycloidura as a synonym) are so closely allied that the females can scarcely be separated, while it is easy to refer the adult males to their respective genera. When more species are known it will probably be necessary to unite them, preserving the name Zuzara for the genus. If that be not done it will be necessary to establish a new genus for Sphæroma scabriculum (Hell.), and perhaps some other species.
In Chapter VII the slight value of Cilicæa (Leach) and Cilicæopsis (n. gen.) as separated from Cymodoce (Leach) is discussed in the treatment of the last-named genus.
The diagnosis is deficient, because mouth-parts and pleopods had been removed before my examination from the two specimens hitherto known, a female with rudimentary marsupial lamellæ and a male.
Of the genus Anoinus, (M.-Edw.). I have only examined a dried specimen from the outside, but Laving dissected specimens of the two other genera, I think it allowable to draw up this diagnosis of the section.
The genus Spelæosphæroma belongs probably to this section, but is omitted, as not only the animal, but the recently published description is unknown to me.
Pfeffer establishes it as the type for a new family, and adds “Die Fam scheint mit den Onisciden am niiclisten verwandt.”
As to the synonymical question on the use of either Dynamene. or Næsa for the present genus, I refer to the footnote on p. 77.
