84 



dark brownish purple. De St. Joseph mentions that some have 

 entirely white branchia'. The same author describes the basal 

 branchial cartilages as forming only two spiral twists, whereas in 

 spirit they appear to have three or four. Their vessels, he says, 

 contain green blood. He observed an example with one of 

 these organs in process of reproduction and represented by 

 twelve white filaments. Both sides are spirally rolled, but the 

 filaments are much shorter than in Spiroi>r(ipliis Sptilhnizdiii 

 from the Mediterranean. 



Along the bases of the whorls an elevated collar or crest of 

 mucous membrane winds, and probably has important functions 

 in directing the streams of water and perhaps secreting mucus. 



The arrangement of the spiral in Bispira as shown in this 

 example is such that in a horizontal section only portions of 

 three rows of branchite appear, for example near the base, the 

 outer being the most complete, the next within (a continuation 

 •of the former) being less, and the third very short. The whole 

 system really consists of a single lamina with its filaments 

 ■spirally rolled on a firm axis which is thickest inferiorly and 

 tapers superiorlv. The upper central filaments are thus shortest, 

 the outer and inferior, the web of which adjoins the collar oi 

 the annelid, are the longest. The spiral attachment thus winds 

 round the axis from above downwards. 



The outer whorl commences on each side at the tentacle, the 

 web of attachment on the left having about two short tapering 

 filaments as supports — before joining the first long branchial 

 filament. On the right the branchial stems are disconnected, 

 the membranous lamina attached to the base of the tentacle 

 abutting inferiorlv on a groove. 



The body is massive, somewhat fusiform in outline — ni so far 

 as it is slightly tapered in front, and still more tapered to a blunt 

 point posteriorly. The bristled segments are about 172 or more. 

 It is rounded on the dorsal surface, flattened on the ventral, and 

 terminates in the anus. A groove commences on the ventral 

 surface at the anus, travels forwards in the middle line to the 

 second post-thoracic segment, bends to the right towards the 

 front of it, and passes obliquely through the segment in front 

 to the space between the anterior and posterior regions, and is 

 there lost, though in some old examples a shallow groove runs 

 forward dorsally a little above the bristle-tufts and is lost at the 

 collar. In front dorsally are the tentacles, and close to their 

 bases ventrallv is a frilled ridge on each side which amalgamates 

 with the inner edge of the massive lips. In all probabilitv the 

 muddy water is conveyed along these to the mouth from the 

 branchial spiral, so that both digestion and respiratitMi are 

 subserved. The lips form two prominent fleshv lobes project- 

 ing forward — d.u-ker in hue distally where slightly enlarged- 

 paler below. Their inner edges are flattened, mdeed, somewhat 



