204 IBLA QUADRIVALVIS, 



I. (Herm.), valvis et pedunculi spinis sub-flavis : basal 7 

 tergorum angulo, introrswn spectanti, hebete, quia mar go 

 carinalis inferior longius quam margo scutalis prominet. 



Hermaph. — Valves and spines on the peduncle yellow- 

 ish : basal angle of the terga, viewed internally, blunt, 

 owing to the lower carina! margin being more protu- 

 berant than the scutal margin. 



Caudal appendages four times as long as the pedicels 

 of the sixth cirrus : rami of the first cirrus unequal in 

 length by about six segments. 



Comple mental Male, with a notched crest on the 

 dorsal surface, forming a rudiment of a capitulum : 

 maxillae well furnished with spines. 



Kangaroo Island, South Australia (Mus. Brit., given by Cuvier to Leach) ; 

 Adelaide, South Australia (Mus. Stutchbury) ; King George's Sound, Voyage 

 of Astrolabe; New South Wales, attached to a mass of the Galeolaria 

 decumbens, (Mus. Hancock). 



HERMAPHRODITE. 



All the external parts so closely resemble those of 

 I. Cumingii, that it would be superfluous to describe 

 more than the few points of difference. The horny 

 substance of both scuta and terga is uniformly yellow ; 

 though in dryed specimens, from the underlying corium 

 being seen through the valves, these generally have a 

 tinge of blue. 



The Scuta, viewed internally, are less elongated trans- 

 versely ; they have their basal margins slightly more 

 hollowed out, and the fold on the upper free and horn- 

 like portion rather deeper. 



The Terga, viewed internally, have the apex of the 

 growing or corium-covered surface higher relatively to 

 the scuta than in I. Cumingii; and the basal angle is 

 much broader, owing to the lower carinal margin being 

 much more protuberant than the scutal margin. The 

 spines on the peduncle are all yellowish-brown, and are 

 rather longer than in Z Cumingii. I observed in three 

 or four specimens, that the lowest part of the peduncle 



