270 



CAPITELLID^ 



hypoderm, which is somewhat thicker on the ridge in the mid-dorsal line, and on each side of 

 the mid-ventral muscle. The hypodermic basement-tissue seems to be feebly developed, for 

 the hypoderm proper clings closely to the well-developed circular muscular layer which lies 

 within it, and encircles the body. In the mid-dorsal line beneath the hypodermic ridge is a 

 special series of short transverse fibres outside the ordinary circular layer, but certain fibres 



vrrv ^ c 

 Fig. 128. — Transverse section of the anterior region of Notomastus latericeus, Sars. Letters as before. 



of which seem to run into it. Immediately within the continuous circular coat is a pair 

 of small and symmetrical longitudinal muscles, which in transverse section are elongate- 

 ovoid with the more acute end external, though the appearance varies according to the 

 preparation. They are covered internally by connective tissue and coelomic epithelium, 

 and at the outer end of the pair is the attachment of a powerful vertical band of muscular 



Fig. 129. — Transverse section of the posterior region of Notomastus latericeus, Sars. 



fibres fixed to the circular coat and basement-tissue. In the middle line is the suspensory 

 membrane of the alimentary canal. A massive almond-shaped lateral muscle then 

 follows, the pointed end being inferior. This and the previous small median muscle of 

 one side probably correspond to the single dorsal longitudinal muscle of other forms, 

 unless it is to be supposed that the next and still more massive muscle is to be likewise 



