BRITISH IJAHINE TDEBELLARIA. 453 



Distribution. — Naples (Schmidt and v. GraflF), Messina 

 (Graff), Sebastopol (Uljanin). 



13. Promesostoma LENTicuLATUM (Schmidt [28]) . Pl.XXXlX, 

 fig. 6; PL XL, figs. 13, 17. 



Length '65 — "7 ram. (i. e. half that of Schmidt^s specimen). 

 Body broadly truncate and slightly convex in front, the antero- 

 lateral margins produced slightly outwards. Behind these 

 it becomes narrower, forming a " neck ; " it then widens 

 towards the middle, diminishing again to the posterior end. 

 The general shape is, in fact, similar to Jensenia (see 

 Jensen [49], pi. iii, figs. 1, 2), but more elongate. Colour to 

 the naked eye scarlet ; this is due to the contents of the 

 extensive gut. Movements extremely active. Epidermis 

 very transparent. Rhabdites few, scattered. Pharynx placed 

 slightly in front of the middle of the ventral surface. Intestine 

 large, corresponding to the shape of the body. The eyes are 

 provided with a large conspicuous lens, which is easily detached 

 from the pigment-cup. The genital aperture is a short 

 distance behind the pharynx. The testes have the usual 

 relations, and lead at their posterior ends into the vasa 

 deferentia, which unite to open into the base of a most 

 remarkable copulatory organ. This is cylindrical at its 

 proximal end, provided distally with a series of triangular 

 chitinous plates ranged round the terminal slit. The whole 

 resembles the tool known as a " rose-bit ^^ or "counter-sink," 

 and used for embedding the heads of screws in wood or metal. 

 The base of this organ is divided into spermatic and granule 

 portions. The germaria are placed posteriorly. On one side 

 the germarium was normal; on the other it was composed 

 of lenticular masses, with difficulty separable optically from 

 one another. The paired yolk-glands occupy the greater 

 part of the sides of the body. 



Habitat. — Two specimens from a tide-pool among corallines, 

 Port Erin, Isle of Man (F. W.G.). 



