ECHINOEHYNOHUS. 99 



caudal end of the female is smooth and rounded. As in other en- 

 tozoa, the integument consists of a fine cuticular external mem- 

 brane, succeeded by a hard, true, fibrous dermis made up of two or 

 more distinct layers. It possesses absorbent powers in a much 

 higher degree than is shared by other kinds of entozoa ; for, during 

 life, as observed by Yon Siebold, Oreplin, Mehlis, and others, these 

 animals are capable of regulating the passage of fluids within and 

 without the body. The integument is succeeded by two muscular 

 layers, one longitudinal and one transverse, the latter being exter- 

 nal. If a male example be next laid open, we may notice in the 

 first place the sac of the proboscis lying in the central line immedi- 

 ately below the so-called neck. This forms a dense muscular sheath, 

 which is connected below, or rather held in its place, by three dis- 

 tinct muscular bands, which severally pass from the coecal end in 

 an outward and downward direction to reach the muscular parietes 

 of the body. The bands in question are termed retractor mus- 

 cles. On either side of the proboscideal sac there is placed an 

 elongated flattened body, which by some is said to open externally 

 at the base of the neck. The two organs form the so-called lem^ 

 nisei which Dujardin conjectured might be salivary organs, but 

 which are now more generally regarded as connected with the 

 water-vascular system. At all events, a system of canals contain- 

 ing fluid granular contents occurs in the walls of the lemnisci, and 

 they are, moreover, intimately connected with a similar system of 

 vascular tubes, traversing the general integument of the body. 

 The lemnisci, which are parenchymatous internally, are also sup- 

 plied with special muscular bands at the outer surface; Below 

 the site of these organs the body is suddenly hollowed out so as to 

 form a large perivisceral cavity, in which we find lodged only such 

 other organs as are concerned in the reproductive process. In the 

 male these consist of two large oval testes placed one above the 

 other in the centre of the cavity, the other being attached to the 

 lower or coecal end of the proboscideal sac by a strong ligamentum 

 suspensoriwm. Two large and tortuous vasa deferentia pass ofl 



