REPORT ON THE PTEROPODA. 
13 
1 . Clio. 
The Head in Clio resembles that of Limacina, but Creseis has the left tentacle very 
little developed, as in Limacina, whilst in the others ( Hyalocylix , Styliola, and Clio, 
s. str.) it is almost as larg;e as the right. 
It has also been shown above, as a distinctive character, that in Creseis the fins are 
provided with a little tentacular lobe on the dorsal margin, as in Limacina. In Hyalo- 
cylix the area on the margin of the fin devoid of muscular fibres is situated towards 
the dorso-lateral angle. In Styliola and Clio ( 5 . str.) this area is found towards the 
middle of the lateral margin. 
The Foot has the posterior lobe rather short in Creseis, short in Hyalocylix, and long 
in Styliola and Clio (s. str.). 
The Mantle is quite open in front in Creseis, Hyalocylix, and Styliola, whilst in 
Clio ( s . str.) its margins are slightly united at the sides, so that the aperture of the 
mantle is narrower than that of the shell. In all four subgenera the lateral lobe of the 
mantle (balancer) is less developed than in the Limacinkke, and is situated on the left 
side. 
The pallial gland (shield) is bilaterally symmetrical in all cases, but presents a 
different appearance in the different subgenera. In Creseis it is homogeneous, like that of 
Limacina. In Hyalocylix (PI. II. fig. 4) a transparent transverse band divides it into an 
anterior and a posterior portion, the former of which further exhibits on each side a small 
distinct triangular patch. In Clio ( s . str.) (e.g., Clio pyramidata, PI. II. fig. 2), in the 
anterior portion, in the centre of a more transparent space, is a median rhomboidal tract, 
on each side of which are two rather narrow bands. 
The pallial cavity, which is ventral in contradistinction to the Limaciniclse, extends 
rather far backwards, owing to the generally elongated form of the genus Clio. 
The Digestive Tract. — The mouth, lips, and the whole buccal mass are disposed as in 
Limacina. The jaws are firmer ; they and the radula have been described and figured 
so often that it is not necessary to dwell upon them further. 
All forms of the genus Clio possess very appreciable salivary glands, which are rather 
short, ovoid, and without any differentiated duct. 
The oesophagus varies in length, being rather short in Clio ( s . str.) and Styliola, long 
in Hyalocylix and Creseis, and of inordinate length in Clio ( Creseis ) virgula; it is 
strongly folded in the direction of its length. 
The stomach possesses, as in the Limacinidse, five large masticatory plates, four 
quadrangular and symmetrical (PI. II. fig. 1 , g), like the corresponding plates of Limacina, 
and a fifth triangular, situated on the ventral aspect, posterior to the preceding (PL II. 
fig. 1 , h). The two ventral quadrangular plates are shorter than the two dorsal (PI. II. 
fig. 5). 
