104 THE VOYAGE OF H.M.S. CHALLENGER. 



than in Culeolus murrayi, and diverge as they recede from the anterior end. The 

 greatest width is reached at about two-thirds of the length of the body from the anterior 

 md. From this point the ventral edge runs with a slight ventral inclination to meet 

 the posterior end, while the dorsal edge curves round as described above. The sides are 

 irregularly but about equally convex. 



The peduncle is not long ; it is thin, wiry, stiffer than in the last species, but not so 

 flexible, and is bent in a gentle curve towards the dorsal side of the body. It is attached 

 to the anterior end of the body, and turns dorsally at a right angle, so as to cross the 

 branchial aperture (PL X. fig. 1). From its point of attachment it runs for a short 

 distance partly imbedded in the test, and disappears on the ventral edge. It becomes 

 thickened at the upper extremity where it is continuous with the anterior end of the 

 body, and is somewhat spread out at its lower end so as to form a base of attachment ; 

 otherwise it is of much the same thickness throuohout. 



The branchial aperture is placed close to the anterior extremity, at the commence- 

 ment of the dorsal edge and immediately below the peduncle (PI. X. figs. 1 and 2). It 

 is sessile but very conspicuous, and, as in the last species, is large, open, and triangular 

 in shape — the base being anterior and the apex posterior. It has a smooth lip, bordered 

 by a ridge, which, on the posterior side, is cut up into a series of blunt papillae placed 

 side by side. The branchial aperture looks almost directly anteriorly. The atrial 

 aperture is at the opposite end, being placed in the centre of the large posterior ex- 

 tremity, and looks directly posteriorly. It is sessile, conspicuous, large, and open. It is 

 bilabiate, and presents the form of a transverse slit, having smooth lips, and a conspicuous 

 raised border on the ventral side (PI. X. figs. 1 and 3). 



The surface is very irregular. It is raised into prominent, rounded, pad-like, longi- 

 tudinally running ridges, separated by deep creases. These ridges are again subdivided 

 by slighter transverse creases into small irregularly-shaped elevated areas, each of which 

 bears in its centre a small but prominent papilla, which may be sharp-pointed. Other- 

 wise the surface of the body is perfectly smooth. The peduncle is finely grooved 

 longitudinally throughout its length. 



The colour of the body is a pale grey, having a bluish hyaline appearance in some 

 parts, and a warmer yellowish tinge in others. The peduncle is rather bluer, being of a 

 pale slate-grey throughout. 



The dimensions are as follows : — 



Length of the body (antero-posterior), 

 Breadth of the body (dorso-ventral), 

 Thickness of the body (lateral), 

 Length of the peduncle, 

 Thickness of the peduncle (average), 



The Test is rather thick. It has a cartilaginous aj>pearance, but is quite soft ; it is, 



