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



mass of tangled filaments which have evidently been rooted in globigerina ooze (PI. XI. 

 figs. 1 and 2). 



The branchial aperture is at the anterior end, terminal, and almost or quite median, 

 being sometimes slightly dorsal. The insertion of the peduncle just at its ventral edge 

 causes that point to be the most prominent part of the anterior end, and so to throw the 

 branchial aperture a little dorsally. The aperture is sessile, conspicuous, and of consider- 

 able size. It has the form of a triangular slit (PI. XL fig. 3), elongated transversely, 

 and having the apex directed dorsally. It has a raised lip all round, cut up into a series 

 of blunt rounded papillae placed closely side by side. The branchial aperture is directed 

 either anteriorly or anteriorly and slightly dorsally. 



The atrial aperture is not so far distant as in the two previously described species. It 

 is situated at the junction of the dorsal edge with the dorsal extremity of the large curved 

 posterior end, and looks dorsally and a little posteriorly. It is sessile but prominent, 

 conspicuous, of moderate size, and slightly open. It has the form of a transversely elon- 

 gated elliptical slit (PI. XL figs. 1, 2 and 4), with a raised lip on both edges, formed, like 

 that round the branchial aperture, of a series of close-set blunt papilla). This aperture is 

 about two-thirds of the way from the branchial aperture to the middle of the posterior end. 



The surface of the body is regular and even, and is pretty smooth. Here and there 

 sprinkled over it there are slight papillae and granulated patches. Pound the posterior 

 end, however, and enclosing the atrial aperture, there is a band of closely placed, slightly 

 larger papillae or processes, forming a structure like that seen in a similar position in 

 Culeolus murrayi. It is quite a narrow band, but is continuous, and forms a ring cutting 

 off obliquely about the posterior fourth of the body from the rest. Dorsally it skirts the 

 anterior margin of the atrial aperture (PI. XL figs. 1, 2 and 4), while its ventral part 

 separates the posterior end from the ventral edge of the body, or may lie even more 

 posteriorly, so that its direction, viewed laterally, is from the dorsal edge ventrally and 

 posteriorly. 



The colour of the body is a pale grey, in some places having a yellowish-white 

 appearance. The peduncle is yellowish-white or of a dirty cream colour. 



The dimensions are as follows : — 



Length of the body (antero-posterior), . . . . . . 2 - 5 cm. 



Breadth of the body (dorso-ventral), . . . . . . .17,, 



Thickness of the body (lateral), . . . . . . . . 1 -5 „ 



Length of the peduncle, . . . . . . . . . 14 „ 



Thickness of the peduncle, ........ 1 mm. 



TJie Test is thin and flexible, but tough. It is almost opaque, being only semi- 

 transparent in parts. The outer surface is rough and irregular, and is considerably 

 coated with Foraminifera, sand-grains, mud, &c. 



In minute structure it is very compact (PI. XII. fig. 1). The matrix is close and 



