ON THE DEVELOPMENT OF LINGULA ANATINA. 75 



ends projected out of the body wall, but in reality the outline of 

 the latter can readily be seen covering the ends of the muscles 

 (PL VI., Figs. 81, 82). 



Although the obliqui extend {obi. ex.) are found in the late 

 6 p. c. stage (PI. VI., Fig. 82) they may conveniently be 

 described in connection with the musculature of the next stage. 



I shall now take up the description of the musculature of 

 the larvœ at the 7-9 p. c. stage. With minor exceptions my 

 results agree with those of Brooks. As the arrangement of the 

 muscles to be described agrees essentially with that of the 10-15 

 p. c. stage, the reader will adequately understand the course of 

 the muscles by reference to the wood-cut B, and to Fig. 128 

 (PI. VIII.). 



The Occlusor posterior (occ. pst.) (Wood-cut B, PI. VIII., 

 Fig. 128). 



This unpaired muscle is formed at the beginning of the 7 

 p. c. stage, arising from the posterior body wall (PL VII., Fig. 

 119). Subsequently it is entirely separated from the body wall. 

 In some cases, however, this muscle lies so closely apposed to the 

 body wall that one might mistake it for a part of the latter. 

 At its first appearance it is composed of a few fibres, but as the 

 larvae grow, the fibres increase both in number and in size. At 

 the 7-9 p. c. stage on surface view it has the shape of an ellipse 

 whose major axis lies in a transverse direction ; it is sometimes 

 crescent-shaped with its concavity directed forward (PL VI., Fig. 

 84, PL VIL, Fig. 116, and PL VIII., Fig. 128). 



The Occlusores anteriores {occ. ant.) (Wood- cut B, PL 

 VIII., Fig. 128). 



