216 PSEUDOBONELLIA, A NEW ECHIUKOID GENUS, 



tinct pit, from the floor of which a definite papilla arose. In 

 section, the apertures were seen to he quite small, and situated 

 on the general body surface a short distance behind the seta?. 

 The body is covered with small, flat-topped papilla?, closely 

 arranged, being separated from each other by well-marked, nar- 

 row furrows. As a result of the bleaching of the bonellin pig- 

 ment during preservation, the body wall was rendered fairly 

 transparent, and the twisted intestine, with its mass of white 

 granular contents, could be plainly seen. 



The body wall. — Dorsally the body wall is very thin, while 

 ventrally it is very much thicker, owing to the greater develop- 

 ment of the musculature in that region. On the outside, next 

 to the very thin cuticle, is an epidermis consisting of a single 

 layer of columnar cells, below which lies the well-developed 

 dermis with highly vacuolated connective tissue, traversed by 

 fibres arranged vertically to the surface of the body. Abundant, 

 branching, gland cells which stain deeply with hematoxylin are 

 lodged in the dermal portion of each papilla and open through 

 the epidermis (Plate x., figs. 8, 9). These glands, no doubt, are 

 responsible for the production of the mucous secretion which 

 gives a slimy consistency to the preservative (formalin), from 

 which it is readily precipitated by the addition of alcohol. 

 Below the dermis are three series of muscles, an outer circular, 

 a middle longitudinal which is about twice as thick as the pre- 

 ceding, and an inner oblique layer (inner circular layer of Sluiter, 

 1891) whose fibres travel partly circularly and partly obliquely. 

 The last series is about half as thick as the outer circular mus- 

 culature. The longitudinal layer is not divided up into separate 

 bundles. The appearance of the body wall in section reminds 

 one of that figured for B. pumicea by Sluiter (1891, Pl.l, fig.2). 



In the proboscis, the first and second series alone are present. 

 The circular layer is well-developed, but it is the longitudinal 

 system which occupies the greater part of the organ (Plate ix., 

 fig.6). The latter musculature consists of two sets of fibres, an 

 outer composed of abundant, closely-arranged, small fibres, and 

 an inner mass consisting of a great number of large fibres, well 

 separated from one another by connective tissue when the organ 





