560 H. LYSTER JAMESON^ 



cular layers and a peritoneum. The "réseau ganglionnaire" of Rietsch 

 and the connexions between epidermis and fibrous or nervous elements 

 which Greeff describes are not found , and such appearances are 

 referred to the distortion of the epidermis consequent upon the pressure 

 exercised by the gland cells. 



The muscular layers have the relations characteristic of most 

 Echiuroids. The muscle fibres have the typical structure of Annelid 

 muscles in transverse section, the striae seen in longitudinally sectioned 

 tissues and in macerated preparations being sometimes parallel to the 

 long axis of the fibre, sometimes spiral. 



An intermuscular fibrillar tissue, identical with the cutis , from 

 which it cannot be sharply separated , exists , and the muscle fibres 

 give attachment to little connective tissue languets which probably 

 connect them to this matrix or to one another. 



The digestive organs agree essentially with those of other Echi- 

 uroids, differing in certain details. They comprise a fore-gut, consisting 

 of pharynx, oesophagus, gizzard and crop, a mid- gut or intestine in which 

 the ordinary relations of the musculature are reversed, and a rectum. 

 The fore-gut is separated from the intestine by a marked constriction. 

 The intestine is divisible into three divisions, the middle one possessing a 

 collateral intestine or siphon, the anterior and posterior bearing a ciliated 

 groove. These structures are ventral in position. The collateral intestine 

 is formed by the cutting oö of the ciliated groove from the cavity of 

 the intestine. Its anterior and posterior openings into the gut difier 

 slightly from one another, the transition from siphon to groove being 

 more gradual posteriorly. A secondary ciliated groove is developed 

 under the siphon in the wall of the gut. Remarkable glands are found 

 in the oesophagus and more strongly developed in the crop. A marked 

 alteration suggestive of degeneration occurs in their nuclei when the 

 secretion is elaborated. It is probable that these nuclei are discharged 

 with the secretion. I have suggested that these glands may function 

 in secreting the mucus by means of which the sand is cemented into 

 the characteristic balls that occur in the intestine. A peri-intestinal 

 sinus occurs but has no connexion with the blood vessels. 



The epithelium of the intestine is much simpler than that of the 

 crop. The peri-anal tissue described by Rietsch is probably referable 

 to epidermal gland cells opening into the rectum. 



The vascular system agrees in its relations with that of Echiurus^ 

 rather than with that of Bonellia. 



