Clare Island Survey — Arohiannelida and Polychaeta. 47 125 



Thelepus cincinnatus (Fabricius). 

 1912. Thelepus cincinnatus. Wollebaek, p. 89. 



This species is very rare in Blacksod Bay, only two specimens having 

 been found there. In Clew Bay, it was usually dredged in mud or muddy 

 sand. Mature specimens were found in August, young specimens in May. 

 Habitat. — Blacksod Bay — Found on the shore on two occasions. 

 Clew Bay — Dredged off Mulranny in 7 fms. ; in Inishlyre 

 Harbour in 2-4 fms. ; in Killary Harbour on two occasions 

 in 7 and 17£ fms. ; near Inishgowla in 8-10 fms. 

 Distribution. — British Isles ; France ; Arctic ; Scandinavia ; North Sea ; 

 east North America ; Mediterranean. 



Thelepides collaris gen. et sp. nov. 

 PL XIII, figs. 30a-e. 



A single specimen only of this interesting form was dredged in Clew Bay, 

 in 15 fathoms. The tube is missing. 



The specimen, which is incomplete posteriorly, is 25 mm. long, and 

 consists of 29 segments, of which 27 bear setae. The sexual organs are not 

 mature. 



The body is only slightly swollen in the thoracic region, tapering towards 

 the head. The abdominal region is cylindrical. The skin is smooth, and 

 does not show the pitted markings so prominent in Thelepus setosus and 

 T. cincinnatus. 



In the anterior region the segments are four times as broad as long, but 

 the length gradually increases, and in the abdominal region the length 

 considerably exceeds the breadth. In the thoracic segments there is a 

 superficial annulation of the skin. 



A conspicuous folded membrane surrounds the mouth (figs. 30a, 30b). In 

 the median ventral line there is a small lobe not connected with the folded 

 membrane. The tentacles emerge in two lateral bunches. 



The first segment has two groups of eyes in a dorso-lateral position. On 

 the ventral side it forms a smooth rounded lower lip (fig. 30b), with its 

 lateral boundaries indicated by the nerve commissures. 



The branchiae occur on the second and third segments (fig. 30a). As in 

 the genus Thelepus, they are slender, cirriform, and unbranched. Each is 

 faintly grooved. On the second segment there are four pairs of branchiae, 

 on the third segment two pairs. These numbers are much smaller than those 

 found in species of Thelepus, and approximate to the condition in the genus 

 Euthelepus Mcintosh, where there is only a single pair of branchiae on 



