66 THE VOYAGE OF II. M.S. CHALLENGER. 



dinal bars are wide, but delicate, and not distant. The transverse vessels are rather irregu- 

 lar, and there are generally several smaller vessels of different sizes placed between each pair 

 of larger ones. Frequently the smaller vessels do not extend the entire breadth of the 

 mesh. The meshes are somewhat variable. Considered as extending from one larger trans- 

 verse vessel to the next, they are generally elongated antero-posteriorly, but may be square 

 or even elongated transversely. The stigmata are of different lengths, and often run across 

 (behind) the transverse vessels ; they are generally straight and all placed longitudinally. 



The Dorsal Lamina is broad but thin and short ; it is quite plain, with no ribs nor teeth. 



The Tentacles are compound and large, sixteen in number, and of two sizes placed 

 alternately. 



The Dorsal Tubercle is prominent, elongated transversely, and having the aperture 

 at the right side. The horns are large, and both coiled outwards. 



The Alimentary Canal, as in the preceding species, is on the left side of the branchial 

 sac, lying antero-posteriorly, and chiefly along the dorsal edge and the dorsal part of the 

 posterior end. 



Genitalia are present on both sides of the body. The gland on the left side lies ven- 

 trally to the intestine, whde the other genital gland occupies the centre of the right side. 



This species, though agreeing with Ascopera gigantea in all important characters, 

 has a very different appearance (PL III. fig. 1). The proportion between body and 

 peduncle is the reverse of that which obtains in the last species, the peduncle beino- here 

 twice as long as the body. The body is somewhat similar in appearance, though much 

 smaller and more compressed laterally. The apertures are placed at the extremities of the 

 anterior end, but the atrial is turned up so as to be directly opposed to the peduncle which 

 arises from the ventral edge of the posterior end. Hence there is a liability to consider 

 the atrial aperture as forming the anterior extremity, and the peduncle the posterior, and 

 one is greatly tempted to describe the animal in this position. It would, however, be 

 distinctly an error, as the morphological anterior end is always indicated by the branchial 

 aperture, and the dorsal edge is that side on which the nerve-ganglion (or, for convenience 

 in practice, the atrial aperture) is placed. In the present case it would make an immense 

 difference and cause utter confusion to follow what seems the natural enough course of 

 considering the two opposite ends of the animal as anterior and posterior (in place of call- 

 ing the one the dorsal edge of the anterior end and the other the ventral edge of the pos- 

 terior end), as what is really the ventral edge, that on the extremity of which the branchial 

 aperture is placed (PI. III. fig. 1), would then become the dorsal, and the right and left 

 sides of the animal would also be transposed. This explains the apparent abnormality of 

 the principal viscera being placed on what seems the right side. 



The test over the surface of the body is rather stronger than that of Ascopera 

 gigantea, but in the peduncle, on the other hand, it is much thinner. 



