The Morphology of a Solenogastre. 113 
point half way to the mouth opening. As just noted some of their 
fibres are continuous with a portion of the foregoing muscle. 
No. 14. One large and several very much smaller pairs of 
muscles are inserted in the wall surrounding the semicircular groove 
and radiating outward and backward attach to the body wall. 
No. 15. On the dorsal side of the body are several pairs of 
muscles usually small (the largest shown in Fig. 7), that attach to 
the buccal wall chiefly in the region of the mouth opening and 
passing backward and dorsally unite with the somatic muscles. 
No. 16. A few small bands attach to the body wall in the 
dorsal (or lateral) side of the animal and encircling the alimentary 
canal and the semicircular groove unite with the body wall ventrally 
(or laterally). Other muscles of much smaller size and extent but 
with similar attachments are more or less irregularly distributed in 
every quadrant. 
No. 17. A fairly strong muscle is attached to the ventral wall 
of the oesophagus a short distance behind the dorsal salivary gland. 
Passing outward and downward it attaches to the body wall. 
Nr. 18. Numerous small fibres attach to the front subradular 
wall of the pharynx and extending forward attach to the body wall 
in the neighborhood of the semicircular groove. 
The foregoing are the more important muscles of the anterior 
part of the body. It is not possible from surface views to gain an 
accurate idea of the remainder and the work of reconstructing them 
from sections is well nigh impossible. It may be said that they 
comprise several small fibres radiating from the buccal wall to the 
body wall; a few from the buccal tube to the semicircular groove; 
many from the semicircular groove to the body wall; and a few 
scattered bands from the oesophagus to the body wall. These 
practically fill all the head cavity anterior to the salivary glands. 
In regard to the mode of operation of these muscles’) a number 
of facts appear with considerable clearness. In the first place the 
general movements of the radula and its supports are essentially 
1) I have examined several cleared and mounted specimens and have 
carefully studied some of these same individuals when they had been 
sectioned and I feel confidant that the foregoing muscles constitute the 
more important or at all events the more highly developed ones in the 
head region. Furthermore in regard to their mode of operation I may 
say in defense of the following paragraphs that they are the result of a 
careful study of models. 
