680 THE VOYAGE OF H.M.S. CHALLENGER. 



No. VI. (See p. 465.) 



Gecid2E, Gray, 1847. 

 Genera. 1. Parastrophia, de Folin. 2. Strebloceras, Carp. 3. Watsonia, de Folin. 4. C cecum, Flem. 



The Caecidae are a group of shallow-water Mollusca, enormously numerous in individuals but 

 hitherto poor in species. As was natural, very few indeed presented themselves in the Challenger 

 dredgings ; and these I had great pleasure in intrusting to one who has so specially made the group 

 his study as the Marquis de Folin. His acquaintance with the subject in general, and his own vast 

 collection of specimens gathered from every quarter of the globe, are the pledges that in what he 

 has now produced nothing known on the subject has been overlooked ; and even those who may 

 hesitate to accept in full his classification will recognise both the general value of this monograph, 

 and the extraordinary perfection with which he has delineated the specimens. 



His Report upon the Challenger collection will be found upon the next few pages, but two species 

 which came into my hands atter his work was completed are recorded here, and a note upon them 

 by the Marquis will be found on p. 689. 



(15.) CcEcum vitreum, Carpenter. 



Ccecum'glafiruml(no\, of Mont.), McAndrew, Brit. Assoc. Report, Geog. Distr. Test., 1854. ' 

 f„ Ivitreum, Carpenter, Monog. Caecidae, Proc. Zool. Soc. Lond., 1858, p. 432, sp. 29. 



February 10, 1873. OffTenerife. 78 fathoms. 



Habitat. — Tenerife. 50 fathoms (McAndrew). 



For the identification of this species the Marquis de Folin is not answerable. It had slipped 

 aside, and was not sent to him with the others. It was, however, identified by me from McAndrew's 

 own specimens in the- Cambridge Museum. 



(16.) Gcecum pollicare, Carpenter. 



CoBcum pollicare, Carpenter, Monog. Caecidae, Proc. Zool. Soc. Lond., 1858, p. 432, sp. 30. , 



February 10, 1873. OffTenerife. 78 fathoms. 



Habitat. — Tenerife. 50 fathoms (McAndrew). 



For this species, in like manner, I am alone responsible. Coming on it exactly as Dr Carpenter 

 says he did on the types of the species, and recognising the peculiar features he refers to, I have 

 presumed to refer the solitary specimen met with to his species. 



