100 PHYSIOLOGICAL SERIES. 



A shell with the muscle attachments outlined in red is 

 mounted below. 0. C. 52 A c. 



Harvey Gibson, Trans. R. Soc. Edin., vol. xxxii. 188;"). 

 p. Cr2l. 



C. 46. A Heteropod (Carinaria tnedtterranea) } from the left 

 side of which the integuments have been removed to show 

 the arrangement of the muscles of the body-wall. Thev 



~ * 



consist of a number of anastomosing bands that completely 

 surround the anterior parts of the body, and are specially 

 numerous in the fin (chiefly propodium), but become fewer 

 and more scattered in the metapodium. The mesopodium is 

 represented by a sucker upon the postero-ventral margin 

 of the fin. They fall into three main groups according 

 to their direction within the body-wall, i. A series rising 

 from the dorsum and passing diagonally backwards round 

 the sides to the ventral surface. ii. The converse of 

 the preceding, passing backwards from the ventral to the 

 dorsal surface, iii. Very delicate circumferential bands. 

 The muscle-fibres are smooth. 



Kalide, Zeitschr. wiss. Zool., Bd. xlvi. 1888, p. 345 ; 

 Wackwitz, Zool. Beitr., Bd. iii. 1892, p. 134. 



C. 47. Two specimens of a Snail (Helix aspersa), showing a com- 

 pound retractor muscle (the columellar muscle) by means 

 of which the whole anterior part of the animal can bo 

 withdrawn into the shell. The muscle originates in three 

 bundles from the columella in the third coil of the shell ; 

 the two lateral bundles spread out in the foot on either side 

 of the mid-line, and also give off a slip of attachment to the 

 apex of each tentacle ; the central bundle is inserted into 

 the buccal mass. A small retractor penis passes diagonally 

 across the body-cavity from the penis to the muscular floor 

 of the pulmonary chamber. In the upper specimen the 

 Snail is seen from the right, in the lower from the dorsal 

 aspect. The several muscle-bundles are marked by black 

 paper. 0. 0. 53 c. 



C.48. A Cuttle-fish (Sepia ojficinalis) from which the skin and 

 viscera have been removed to show the muscles. 



The mantle and funnel have also been longitudinallv 



