288 DISCOVERY REPORTS 



to the internal shell of certain Gastropods (Pleurobranchs, Marsenia). The anatomy of 

 the present species has been very fully described by Vayssiere {op. cit., pp. 174-185). 



Distribution. Mediterranean. Off South-west Ireland (Massy, 1909). Off Gibral- 

 tar to Bay of Biscay (Bonnevie, 1913). Gulf of Guinea (Meisenheimer, 1905). 



Genus Cymbuliopsis, Pelseneer, 1888 



Cymbuliopsis intermedia, Tesch, 1904. 



St. 268. Young-fish trawl, 100-150 (-0) m. : 13 specimens and 2 conchae; i m. tow-net oblique, 

 73-0 m. : 3 specimens and 32 conchae; i m. net horizontal, 73-0 m. : 11 conchae. 

 St. 270. Young-fish trawl, 200 (-0) m. : 30 specimens and 1 1 conchae. 



The genus Cymbuliopsis is distinguished from Cymbidia and Gleba "by the presence 

 of a shell with a very large cavity and thin walls. The animal very closely resembles 

 Gleba, having a proboscis free throughout its length, a fin without ventral lobe, and 

 neither radula nor jaws. As far as I can judge, however, it differs from Gleba by the 

 three very distinct muscular systems in the fin, and in the absence of the indentations 

 on the fin margin. As only very few species of both these genera are known, it is very 

 probable that other forms, not yet discovered, will link together the two types" (Tesch, 

 1904, p. 57). This author {loc. cit., p. 59) describes the type specimen as follows : " The 

 shell exhibits the usual characters of Cymbuliopsis. The aperture is always somewhat 

 longer than half the length of the shell. In the distribution of the tubercles I could not 

 observe any regularity ; on the aboral surface are some which are smaller, more closely 

 grouped together; at the ventral margin there are none (figs. 102, 104). This character 

 of the shell agrees partly with what is found in Cymbuliopsis vitrea, Heath and Spaulding. 

 Aperture unarmed, thickened lateral sides; these thickenings disappear towards the 

 ventral margin. Tubercles at the oral surface sometimes fused into mere uneven- 

 nesses, separated by shallow grooves. Animal as in other species of Cymbuliopsis; pro- 

 boscis short and broad, tentacle very short; fins with three distinct systems of muscles; 

 anterior border of the fins scarcely projecting beyond the ventral margin of the shell 

 (almost as in Cymbuliopsis calceola); pallial gland twisted to the left, with three trans- 

 parent bands. Dimensions: 39-23 mm. Shell of St. 144 : 30 mm. Colour of the shell: 

 generally transparent, sometimes yellowish, or even dark brown (alcohol- and formol- 

 specimens)". 



The forty-six specimens with fifty-six conchae recorded above were captured off 

 Elephant Bay, West Africa. The animals measure 27-50 mm. across the fins and the 

 conchae are 14-42 mm. in length. Only one individual and seven shells were taken by 

 the Siboga Expedition. 



The transparent fins are crossed and re-crossed by three sets of muscles, while the 

 soft viscera are protected by the glassy slipper-like concha studded with knobs glittering 

 like crystal. The specimens were preserved in formol and all the conchae were trans- 

 parent, none showing the yellowish or dark brown tints observed in some of the Siboga 

 conchae. With this exception the present specimens are in close agreement with the 

 figures given by Tesch (1904, pi. iv, figs. 100-104). 



