PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 401 



The forms of lowest organization and least specialized cliaracters 

 among those already known are those which inhabit the deeper water; 

 hence there was reason to snppose that features of much interest would 

 be exhibited by the few specimens which had just been brought up 

 from much greater depths than any from which limpets had hitherto 

 been obtained. 



The examination was rendered more complete by the possession of 

 additional specimens which are contained in the deep-sea collection from 

 the Antdles made hy Prof. Alex. Agassiz and Lieutenant-Commander 

 Bartlett, U. S. N., on the United States Coast Survey steamer Bhike. 

 These atibrded valuable confirmation of impressions derived from the 

 study of the material obtained from Professor Verriil. 



Some of the specimens obtained are of unusual interest as showing a 

 combination of characters which has heretofore been unknown in an- 

 imals of the same order. While the shells present few salient features, 

 the soft parts show extraordinary and unexpected characters. They 

 are divided into representatives of the orders Rhiphidoglossa, Docoglossa, 

 and Polyplacipliora. The Bocof/Ioasa comprised representatives of both 

 the suborders Abranchiata and Referobranchiata, but all somewhat 

 anomalous in their characters. It is in the first-mentioned order, how- 

 ever, that the richest results were obtained, since it appears necessary 

 to separate the three species obtained into two genera, representing 

 each a family, which diifers by apparently sound characters from any 

 hitherto known, and which it has therefore been necessary to describe 

 as new. 



Almost all the species appear to be blind. 



Order RHIPHIDOGLOSSA. 



Family COCCULmiD^ Ball. 



Shell patelliform, not nacreous, symmetrical, with an entire non-sinu- 

 ated margin, and a posteriorly inclined apex with a deciduous sjiiral 

 nucleus. Muscular impression horseshoe-shaped, interrupted over the 

 head. 



Animal with a prominent head and muzzle, two tentacles as in Lcpe- 

 tidw ; gill single, plumose, asymmetrical, resembling that of Acmes idee, 

 extending between the under surface of the mantle and the foot (from 

 a point above and behind the head) backward on the right side, attached 

 only at its base. Anus anterior, opening above and behind the head. 

 Mantle margin plain; sides and margin of the foot without papillae- 

 or ornamental processes excei^ting two filaments, one on each side of 

 the jnedian line, between the mantle and the foot-disk behind. Eadulai 

 with a small or moderate rhachidian tooth (in the known sjiecies), three 

 incQuspicuous laterals with denticulate cusj^s and a fourth dentate^, 

 Proc. Nat. Mus 81 2G April S4, 1 8 89.. 



