178 



BRITISH PARASITIC COPEPODA. 



its dorsal aspect. Genital segment furnished with two 

 pairs of tridigitate appendages on the under side and 

 with three pairs of somewhat similar digitiform pro- 

 longations on the lateral aspect, the posterior prolon- 

 gations being the larger; these latter appendages 

 surround and nearly conceal the short, stout, and 

 flattened ovisacs ; several median processes also occur 

 on the dorsal aspect of the genital segment. 



Antennules short and moderately expanded. An- 

 tennse prehensile and provided with stout terminal 

 hooks. Mandibles and other mouth -appendages 



a b 



One of the ovisacs of Chondracanthus zei. 



similar to those of Chondracanthus cornutus. Thoracic 

 legs indistinctly biramose, and their structure some- 

 what rudimentary. Ovisacs, which are short and con- 

 tain numerous small ova, compressed laterally so as to 

 have a broadly and somewhat obliquely ovate outline ; 

 not extending beyond the ends of the prolongations 

 described above. Colour white tinged with red. 

 Length about 12 mm., but the size somewhat variable. 



Male. The male of this species does not appear to 

 differ greatly from that of Chondracanthus cornutus in 

 size and structure. 



Habitat. Parasitic on the gills and gill-arches of 

 the dory (Zeus faber). Polperro, Cornwall (A. M. 

 Normaii). Plymouth (Baxsett- Smith). Firths of Forth 



