90 LEPAS AUSTRALIS. 



nearly equal ; internal basal rim rather wide, sometimes 

 furrowed ; basal margin considerably curved inwards. 

 Terga rather wide ; basal angle blunt ; angle formed by 

 the two occludent margins blunt and rounded. Carina 

 {fig. 5 a) with the apex blunt, flat ; the middle part gene- 

 rally very broad ; much constricted above the fork, where 

 it is internally deeply concave, and externally carinated ; 

 fork twice as broad as the broadest upper part of the 

 valve ; with the prongs flat, broad, thin, pointed, diverging 

 at about an angle of 75°, with the intermediate rim not 

 at all reflexed ; the fork generally not deeply imbedded in 

 the chitine membrane of the peduncle, so as to be quite 

 easily visible externally ; sometimes there is an internal, 

 transverse, depressed line on the fork. In young specimens, 

 with the capitulum about a quarter of an inch long, the 

 fork of the carina is not developed, the lower slightly in- 

 flected portion consisting simply of an oval plate, twice 

 as wide as the upper part. Until I had carefully ex- 

 amined a perfect series, showing the gradual changes in 

 this part, I did not doubt that the young specimens formed 

 a distinct species, and named it accordingly : the short- 

 ness of the penis first made me perceive that the specimens 

 were immature. At this early age, I may add, the fila- 

 mentary appendages were not developed. Peduncle either 

 quite short, or as long as the capitulum, close under which 

 it is considerably constricted all round. 



Filamentary Appendages. — Two on each side : one long, 

 tapering, placed on the prosoma (in one specimen repre- 

 sented by a mere knob), and the second shorter, situated 

 on the posterior margin of the SAvelling beneath the first 

 cirrus. 



Mouth. — Maxillae, with three large spines at the 

 upper angle, and with the first step distinct, but narrow ; 

 mandibles with five teeth; in young specimens the in- 

 ferior point ends in a single spine ; sides of the supra-oral 

 cavity very hairy ; the membrane, forming the inner fold 

 of the labrum, yellow and thickened in the form of a spoon. 



Cirri.- — In the posterior cirri there are, at the upper 



