362 Transactions.— Zoology . 



fully figures the onale. Both sexes were taken by Heller off 

 an undetermined species of shark caught at Auckland. I have 

 not met with this species. 



Genus Cecrops, Leach. 



1. Cecrops laircUlii, Leach. PI. XXVI., fig. 3, a-f. 



This well-marked and well-known form appears to be the 

 only species of the genus. M. -Edwards (" Hist. Nat. Crust.," 

 vol. iii., p. 474) records it as being found on the branchiaa of 

 the tunny {snr les braiichies dii thon), but, with this ex- 

 ception, which may have been stated in error, it is invariably 

 found as a parasite on sun-fishes of various species. Thus 

 round the English coasts it is frequently taken on the gills of 

 Orthagoriscus moUe (Baird : "Brit. Entomostraca," p. 293). 

 It is also recorded from the same species taken on the east 

 coast of the United States. On the Pacific coast of the States 

 it occurs on the gills of Diodon. 



The body of this animal is about an incli long, and is 

 thick and short. The carapace bears two rounded prolonga- 

 tions in front, which represent the frontal lamella? of the pre- 

 ceding genus, and which in this species are rather closely 

 anchylosed to the cephalothorax. The penultimate thoracic 

 segment bears a dorsal shield notched at the posterior margin, 

 which corresponds to the dorsal lamellae in Dincmatnra. The 

 last segment of the thorax bears a very large dorsal shield, 

 deeply notched on the hind margin, and which extends beyond 

 and completely covers the abdomen. Seen from the underside 

 tlie abdomen is dilated and 2-lobed behind, and is covered in 

 front by the greatly-enlarged bases of the fourth pair of feet. 

 The. first antennce are small, and are produced at the angles 

 of the frontal lamella. The second anteium are powerfully 

 developed, and end in strongly-curved brown horny hooks. It 

 is by means of these organs and the powerful hooks of the 

 second foot-jans that the animals attach themselves to their 

 hosts. The oral yroboscis is relatively very short, as the 

 animal appears to bury itself rather deeply in the tissues of 

 its host. The feet are small, and bear either short spines or 

 setae ; but the latter, though often finely serrated along their 

 edges, never bear the feather-Uke fringes of the same organs 

 in Dinematura. In the first three pairs both branches are 

 2-jointed. They do not end in hooks as stated by M. -Edwards, 

 but in each case the short inner branch bears 3 seta? and a 

 few (except in the first pair, which has none) short spines 

 on the terminal joint. In the first pair the outer branch ends 

 in 3 set» and 4 spines ; in the second pair the 1st joint 

 ends in a powerful curved spine, while the 2nd bears several 

 marginal seta> and small spines ; in the third pair it ends in 

 2 (or 3) seta^. In the fourttt pair the basal joint is developed 



