Clare Island Survey — Arvhianuelida and Pob/chaeta. 47 101 



eyes are arranged in an almost straight transverse line, but the usual 

 condition is that shown in fig. 24 A. The first and second segments closely 

 resemble those of A. oxycepliala as figured by Mesnil (1896, pi. x, figs. 21, 

 22). The number of branchiae is only 10 pairs or rarely 11, as against 22-23 

 pairs always found in Irish specimens of A. oxycepliala. The shape of the 

 branchiae and lamellae in the anterior segments does not differ from the 

 condition found in A. o.rycepkala (Mesnil, 1896, pi. x, fig. 23). The setae 

 in these segments are all slender, with a delicate wing, and are not clotted. 

 There is in each foot a row of long slender setae, and a row of shorter stouter 

 setae, and the dorsal setae are longer than the ventral setae. Behind the 

 11 th foot, the lamellae decrease rapidly in size, and are inconspicuous in the 

 posterior part of the body. Winged crochets appear in the ventral division 

 of the 31st foot, and in the dorsal division of the 36th foot, agreeing fairly 

 closely with A. oxycepliala in this respect. The crochets differ from those of 

 A. oxycepliala in having three teeth at the distal end. The large main tooth 

 (fig. 24 e) is bent at right angles to the shaft. The middle tooth is short and 

 pointed, and outside this is a short blunt tooth. 



In the 78th foot (fig. 24 c) the dorsal division contains 4 crochets and 

 6 slender capillary setae. The ventral division has 5 crochets and 6 capillary 

 setae, of which the two ventral are longer and stouter than the others, with a 

 pronounced double curvature. The lamellae are rendered conspicuous by the 

 presence of long finger-shaped glands, of a deep amber colour (fig. 24 d). The 

 anal segment (fig. 24 b) bears two pairs of cirri, the ventral pair being the 

 shorter. In A. oxycepliala the anal segment bears two lateral plates, one on 

 each side of the anus, and each plate has 3-5 cirri (fig. 25), usually 4. 



The points which distinguish this species from A. oxycepliala may be 

 summarized as follows : — (1) Smaller size; (2) smaller number of branchiae, 

 there being 10 or 11 pairs as against 22 or 23 ; (3) three teeth on the crochets 

 as against 2 ; (4) only two pairs of anal cirri, as against 3-5 pairs in 

 A. oxycepliala. 



Mature specimens were found in May. 



Habitat. — Clew Bay — Dredged on four occasions, in 9-24 fms. This 

 species was also found in Berehaven. 



Prionospio Steenstrupi Malmgren. 



1S67. Prionospio Steenstrupi. Malmgren, p. 93. 1880. P. S. 



Langerhans, p. 90. 1897. P. S. Mesnil, p. 90. 



Three species belonging to the genus Prionospio have been described at 

 length from European shores. Of these P. plwmosa (Sars, 1873, p. 63) seems 

 Lu be distinguished by the shape of the head, the anal segment, and the very 



