llersilici (Clausldium) vancouveretisis. 8.") 



Apparently only one species^ Hersilia (CAausidium) apodi- 

 foi-mis (Philippi), has been recorded, and it occurs in the 

 Adriatic and JNIediterranean. Dr. Cerruti, of the Zoological 

 Station at Naples, very kindly sent some parasitic copepods 

 from Callianassa subterranea which tally with the published 

 descriptions of Hersilia apodifoi'mis. 



On comparing- this species with the one from Vancouver 

 Island, I concluded that the latter presented diti'ereuces 

 which entailed the formation of a new species ; 1 have hence 

 named it Hersilia vancuuverensis. 



The genus Hersilia may be distinguished from the other 

 genera comprising tlie family Hersiliidee by the following 

 points * : — 



Hersilia. — The mandible consists of two accessory pieces 



besides the tooth (PI. II. ligs. 2 & 2 a). 

 Giardella. — The mandible resembles the above, but the 



maxillipeds of tiie male have the distal joint in the 



form of a long curved claw\ 

 Hersiliodes. — The mandible consists of three accessory 



pieces besides the tooth. 



Specific characters of Hersilia (Clausidiuni) apodiformis 

 {Ptdlippi). 



Female. — Length 1-35 mm. 

 Carapace practically covering abdomen. 

 Abdomen rather slender. 



Antennules depressed, few hairs on anterior margin. 

 Mandibles bearing a tooth with serrated edges and no 

 hairs (fig. 2 a) . 



No gap between maxillipeds and first thoracic legs. 

 Fifth thoracic leg slender, no fine hairs (fig. 3 a). 

 Infects Callianassa subterranea. 

 Hub. The Adriatic and Mediterranean. 



Specijic characters of Hersilia (Clausidiuni) vancouverensi:^ 

 sp. n. (PI. II. fig. 1.) 



Female. — Length 1"6 mm. 



Carapace only reaches to last thoracic joint. 



Abdomen long and broad. 



* E. Cauii, 1888. 



