58 



Three species have been described in literature. Tliey are the following : 



1. "■ Cy?nóulia' ovata Quoy and Gaimard. 



2. "■ Cymdulia" calceola Verrill. 



3. Cymbuliopsis vitrca Heath and Spaulding. 



"^ Cytnbulia' ovaia is very imperfectly known ; I shall discuss this species further on. 



The summary description ^) given by Verrill, of "" Cymbulia' calceola and especially the 

 smallness of the rather schematical figure ") does not allow absohite certainty as to the specific 

 distinctness of the species, about which, however, we possess a rather extensive anatomical and 

 histological study by Peck ^). It is possible that the "" Ticdeniannia' mentioned by Boas *) may 

 be identical with "■ Cyiiiónlia' calceola. At any rate tlie specimen of Boas is a Cyuibjiliopsis as 

 is elucidated by the shortness of the proboscis and the three distinct muscular sets in the fin. 



Cymbuliopsis vitrca '") is somewhat better known ; it seems to resemble very closely the 

 preceding species. Perhaps it is the same as Corolla speetabilis^ and consequently also identical 

 with the form obtained by the Challenger Expedition "), these forms occurring in the same 

 locahty (North Pacific Ocean). 



None of the specimens of Cymbuliopsis in the Siboga-material can be identified with any 

 of the foregoing species. At least one new species may be established. Taking into account 

 the incompleteness of the description and the figures, given by Ouoy and Gaimard, it remains 

 doubtful whether the specimens from the British Museum, described by Pelseneer ''), belong 

 really to Cymbuliopsis ovata. The same is true of Cymbuliopsis calceola., the anatomy of which 

 was studied by Peck (see above). The diagnosis of this species, procured by its discoverer, is 

 insufficiënt. I have tried to give a synopsis of the species of Cymbuliopsis, actually known. 



Synopsis of the species. 



1 . Shell somewhat pointed at its ventral margin ; aperture shorter 



than half the length of the shell . Cymbiiliopsis ovata. 



Shell rounded at the two extremities, aperture longer than half 

 the length of the shell 2. 



2. Fins projecting beyond the ventral margin of the shell almost 



half its width Cymbuliopsis vitrea. 



Ventral margin of the shell extending nearly as far as the 

 anterior border of the fins 3. 



3. Tubercles regularly placed all over the shell Cymótiliopsis calceola. 



Tubercles irregularly placed, smaller and closely grouped together 



on the aboral surface of the shell ; entirely absent at the ventral margin Cymóuliopsis intermedia. 



1) In: Amedc. Journ. Sci. and Aits, voL XX, p. 392 — 394, iSSo. 



2) In: Tvansact. Connect. Acad., voL V, pi. LVIII, fig. 33. 



3) Stud. Biol. Lab. J. Hopkins Univ., vol. IV, p. 335 — 553. 



4) Spolia atlantica, p. 141, p. 3, fig. 31. 



5) Heath & Spaulding, Proc. Ac. Nat. Sci. Philadelphia, vol. LUI (igoi), p. 509 — 511). 



6) Pelseneer, Chall. Rep., LXV, p. 104. 



7) L. s. c. p. 100, pi. II, figs. 15 — 16. 



