DASYBRANCHUS (?). 289 



which the perivisceral cavity is crowded with sperm-cells surrounded by a circle of 

 smaller pale cells, so that the author compares them to floating testicles. The branchiae 

 are transparent, non-cilated, and contractile (though Claparede could see no muscular 

 fibres), and have areola! ed hypoderm. 



De St. Joseph 1 describes Notomastus exsertilis from St. Jean-de-Luz, a large species 

 about 8 mm. in diameter and 800 mm. long, as possessing exsertile branchiae (about 20) 

 similar to those of Dasybranchus, to which genus it may probably be relegated. 



In an example from Concarneau, De St. Joseph found the branchiae covered with 

 Rh abdostyla arenicolde, Fabre Domergue. 



Dasybranchis is the giant of the family, for Bisig and Lo Bianco found examples at 

 Naples about a yard in length and more than half an inch in diameter. 



A fragment of the middle region of what appears to be a Dasybranchus was dredged 

 in the ' Porcupine ' Expedition of 1870, off Cape Sagres, in forty-five fathoms. The 

 hooks agree with those of D. caducus. 



Dasybranchus, fragment. 



Dredged in the ' Porcupine ' Expedition of 1870 at Station 8, on the Channel slope, 

 257 fathoms. 



This form is represented by a fragment of the posterior end with a small median 

 anus surrounded by a papillary margin, the two largest papillae being ventral. The body 

 is slightly flattened ventrally, rounded dorsally, and with distinct segments. Moreover, 

 along each side dorsally is a row of simple branchiae, one or two in each segment. They 

 are absent from the anterior part of the fragment, and cease before reaching the anus. 



Dasybranchus (?). 



Fragments of the anterior and middle region of a form which appears to be near 

 Dasybranchus (?) were dredged in 80 to 100 fathoms on muddy sand in St. Magnus Bay, 

 Shetland, by Dr. Glwyn Jeffreys in 1867. Certain differences, however, are apparent. 



In what seems to be a portion of the anterior third the ventral ridges for the 

 hooks extend round the edges of the flattened body to the dorsal surface, where they 

 cease. No hooks could be found dorsally, that is, no special dorsal ridges for hooks are 

 present, and thus it differs from Dasybranchus. 



The dorsal surface is rounded and lobed, and the walls are thin, so that in the 

 fragments of the middle (?) the muddy contents and reddish-orange hue of the gut shine 

 through the wall. 



The ventral surface is thick and flattened in front, with a median ridge, which, 

 however, is absent from the posterior fragments. These are only ridged transversely by 

 the row of hooks, which are minute, have a very short main fang, two teeth above 

 it, and conspicuous wings. The ventral longitudinal muscles are greatly developed. 

 The intestine is filled with greyish muddy sand. 



1 ' Ann. Sc. nat./ 9 e ser., t. iii, p. 169, pi. ii, figs. 44-47, 1906. 



160 



