BY THE REV. J. E. TENISON-WOODS. 1075 



in the head of insects. All the Cyclophoridaj have similar organs. 

 The radula has the following formula (2, 1, 1, 2) x 66. It is 

 long, a little curved at the end, but relatively shorter than 

 amongst the most of the Cyclophoridse. The teeth are in oblique 

 rows from the median line to the outer margin. The central 

 teeth are a little oblong, slightly constricted in the centre like an 

 hour-glass, and widely and roundly notched at the base. There 

 is a central wide, short, obtuse cusp, with the rudiment of a 

 lateral one. The first lateral teeth are larger, oblique, elongate, 

 with a narrow base, curving over outwardly on the summit in a 

 direction opposite to the other teeth. The tree edge is bicuspid, 

 the outer short, wide, obtuse, the inner small and short. The 

 two marginal teeth ai-e bicuspid, the internal cusp more feeble 

 than the external, which is triangular. 



M. Fischer, in the "Manuel de Conchyliologie," p. 71, gives 

 liis reasons for classing Hyhocystis betwef-n Papina and Cataulus, 

 but he admits that it differs from the majority of Cyclophoridse 

 l>y its bicuspid marginal and lateral teeth, and the obtuse cusps 

 of the median tooth. These characters united to those of the 

 shell and of the operculum determine the genus. In the posi- 

 tion of Hyhocyatis Dr. Pfeiffer takes a different view, and places 

 it in the great family of Cyclostomacese, in the sub-family 

 Cyclotea. Stoliczka (Jour. As. Soc. Beng. 1871, p. 150) agrees 

 with M. Fischer. 



The following is the explanation of the figures given in the 

 plate : — 



Fig. 1. Animal of Hyhocystis elephas, De Morgan, from a 

 female specimen preserved in alcohol. The head and foot are 

 shown in front — M, edge of mantle ; T, tentacles ; E, eye ; F, 

 sole of foot. 



Fig. 2. Male specimen of the same ; head and foot shown in 

 front— M, mantle ; T, tentacles ; E, eye ; F, foot ; V, verge. 



Fig. 3. Same male specimen shown in profile from the right 

 side — T, tentacle ; B, buccal orifice ; F, foot ; V, verge. 



