AND ON THE NORTH EAST COAST OF ENGLAND. 65 



crateriform opening — this condition seeming to point to a 

 parasitic life. Various hypotheses were put forward, but it 

 was reserved for Professor A. Giard, of Paris, to discover the 

 real host of the parasite in certain annelids belonging to the 

 genus Polydora. Polydora is a marine worm which builds 

 and lives in, a leathery tube. One of M. Giard's specimens 

 of Thamnaleiis was found just inside the tube, clasping the 

 body of the worm, others in the body-cavity of the worm 

 itself, which seems to be the normal position. The life-history 

 remains to be worked out, but it seems probable that after 

 hatching from the &gg the young Thaumaleus finds its way 

 through one of the nephridial pores of the annelid into the 

 body-cavity, there attaining its adult form, after which it 

 escapes, produces and discharges its reproductive cells, and 

 seeing that owing to the absence of alimentary organs it 

 cannot feed, must soon die. 



The specimen here noticed was found in a bottom-net 

 gathering made at CuUercoats in July, 1900. It would appear 

 that it is in the warmer months of the year that free-swimming 

 specimens are usually taken. 



It may be well here to give the diagnostic characters of the 

 family and of its two genera, according to Giesbrecht. 



Fam. — MonstriUidcB. 



" Ampharthrandria " in which the hinder antennae, man- 

 dibles, maxillae, maxillipeds, and rostrum are wanting in both 

 sexes ; the eggs of the female borne in a forked process 

 springing from the ventral surface of the genital segment, 

 which in the male forms a process ending in two projections ; 

 abdomen of the male incompletely segmented. 



Genus Thau??ialetis, Kroyer. 



Between the genital segment and the furca, in the female 

 only one, in the male, two segments ; fifth pair of feet wanting 

 in the male; furca bearing three setae in the female, in the 

 male three or four. Female. — Cephalothorax four-segmented, 

 abdomen three-segmented. Anterior antennae 3-4 jointed, 



E 



