BY THE HEV. 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 Cyclophoridee. 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 free edge is bicuspid, 
the outer short, wide, obtuse, the inner small and short. The 
two marginal teeth are bicuspid, the internal cusp more feeble 
than the external, which is triangular. 
M. Fischer, in the “Manuel de Conchyliologie,” p. 71, gives 
his reasons for classing Hylocystis between 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 chai-acters united to those of the 
shell and of the operculum determine the genus. In the posi- 
tion of Ilyhocyatia Dr. Pfeiffer takes a different view, and places 
it in the great family of CyclostomacecB, in the sub-family 
Cyclotea. Stoliczka (Jour. As. 8oc. Beng. 1871, p. 150) agrees 
Avith 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 pre.served in alcohol. The head and foot are 
shown in front — M, (^dge of mantle ; T, tentacles ; E, eye ; F, 
sole of foot. 
I'ig. 2. Male specimeji 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. 
