148 COE 



main portion of the longitudinal muscles of body walls. In no other 

 species, so far as I am aware, has any such condition been described, 

 though an approach to it is- met with in A. nebulosus ^ where the 

 submuscular glands develop to such an extent as to form a distinct 

 layer which divides the longitudinal muscular layer into an outer and 

 an inner portion. 



An unusual amount of parenchyma surrounds the muscles, nerves, 

 proboscis sheath, esophagus and other organs. 



Alime7itary Canal. — Especially remarkable is the short extent of 

 esophagus, which separates from rhynchodieum just in front of brain, 

 and enlarges posterior to this organ, as usual. Instead of extending 

 far posteriorly, however, as in most related species, it is only about 

 twice as long as the distance from tip of snout to brain. It then enters 

 the dorsal wall of the intestine, the anterior portion of which in this 

 case corresponds in position and liistological structure to the intestinal 

 caecum of other fonias, although it does not end blindly. An ex- 

 tremely short caecvuii proper is, however, present and extends forward, 

 with a few pairs of lateral lobes, for a very short distance anterior to 

 the posterior opening of esophagus. 



The portion of the canal posterior to the esophagus which corre- 

 sponds to the caecum of other forms extends backward for a long dis- 

 tance before merging into the intestine proper. This condition has 

 evidently arisen from the disappearance of the long, slender pylorus 

 of the typical Hoplonemertean, so that the esophagus opens very near 

 the anterior end of the long ca3cum, instead of far back, as in most 

 other members of the order. I shall therefore refer to the cjecum all 

 that portion of the alimentary canal which lies anterior to the intestine 

 proper and exhibits lateral diverticula. This will include the short 

 caecum proper, together with the intestinal canal back as far as the in- 

 testine proper. 



The character of the epithelial lining of esophagus agrees with that 

 in related species. Where the esophagus enters dorsal wall of caecum, 

 however, a marked change in the character of its epithelium appears, 

 as in other forms. Both the caecum and the caecum proper have 

 the same anatomical and histological peculiarities. Both send off 

 paired lateral diverticula, wliich are closely placed together, of rather 

 small size (pi. xviii, fig. 3), and extend laterally somewhat above the 

 lateral nerves. 



The histological structure of the caecum is as in related species, 



'Coe, Proc. Wash. Acad. Sci., in, p. 49, p1. xi, fig. i, 1901 ; also previous 

 article, paged identically. 



