674 ON CRUSTACEA BROUGHT BY DR WILLEY FROM THE SOUTH SEAS. 



Habitat. Sandal Bay, Lifu, Loyalty Islands, and New Britain. Aurivillius' specimea 

 was found attached to the umbilicus of Nautilus umbilicatus. 



Gex. Megalasma, Hoek. 

 1883. Megalasma, Hoek, Challenger Reports, vol. 8, Cirripedia, p. .50. 



Hoek defines the genus as follows : — Valves five, approximate ; carina extending 

 only to the basal points of the terga, with its lower end truncated and ver}' wide. 

 Scuta triangular, with their umbones at a considerable distance from the rostral angle. 

 Mandibles with four teeth ; maxillae slightly notched, with the lower part of the edge 

 slightly prominent; anterior ramus of the first cirrus much thicker than the posterior 

 ramu.s ; the two rami of the second cirrus nearly equal ; caudal appendages uniarticulate, 

 short and spinose at the extremity. 



Megalasma striatum, Hoek. 



1883. Megalasma striatum, Hoek, Challenger Reports, vol. 8, Cii'ripedia, p. 51, pi. 2, 

 figs. 5—9; pL 7, figs. 8, 9. 



A notable character of this species is that ' the short peduncle is quite covered 

 b}' the capitulum,' producing the impression at the first glance of our having to do 

 with a pedunculate cii-ripede devoid of a peduncle. The species is fully described 

 and figured by Dr Hoek. According to his description of the mouth-organs, these 

 show a near resemblance to those of Oxynaspis aimvillii described in this report. 



Length, 9'5 mm. One of Dr Hoek's specimens was 11 mm. long. 



Habitat. Blanche Bay, New Britain, on Echinus-sj)iiies measuring two to three 

 inches in length, and carrying also some small Balanids, Foraminifera, etc. 



.J Gex. Oxyxaspis, Darwin. 



1851. Oxynaspis, Darwin, Lepadidae, Ray Soc, p. 133. 



1893. Oxynaspis, Aurivillius, K. Svenska Vet.-Akad. Handl., vol. 26, No. 7, p. 38. 



Darwin's account of this genus is: — 'Valves 5, approximate; scuta with their 

 umbones in the middle of the occludent margin ; carina rectangularl}' bent, extending 

 up between the terga, with the basal end simply concave. Mandibles with four teeth ; 

 maxillae notched, with the lower part of edge nearly straight, prominent ; anterior 

 ramus of the second cirrus thicker than the posterior ramus ; caudal appendages, 

 uniarticulate, spinose.' 



The single species assigned to the genus by Darwin was Oxynaspis celata, found 

 attached to an Antipathes, from Madeira. In 1892 Aurivillius introduced a new species, 

 Oxynaspis patens, also attached to an Antipathes, taken at a considerable depth off 

 the Island of Anguilla, in the sea of the Antilles. Besides a much larger size and 

 differences in the shape of the valves, this species is distinguished from Darwin's by 

 entii-e absence of caudal appendages, so that in regard to these the generic account 

 must be modified. Also to some extent the first maxillae differ in the two species. 

 Darwin says of the capitulum of his species, that "it seems always entirely covered 



