138 HENRY DAVIS ON A LARVAL CURRIPEDE. 



is furnished by its carapace. Darwin speaks of it as being pro- 

 vided with two points at the posterior end, and with a pair of pro- 

 jections, like short horns, in front (which he thinks may be called 

 the ears), but he says nothing of the very noticeable corrugated 

 crest running over the back at the junction of the valves ; and, 

 failing any published figures of this larva, some doubt may be 

 attached to the specific name I have appended. 



The external microscopic structure is very interesting, and has 

 been strangely neglected — only " marks and lines " are recorded — 

 but under a binocular microscope, with a quarter inch objective and 

 reflected light, we can see the surface covered with deep thin walls 

 or ridges, generally parallel but in parts tending to confluence ; 

 their outer edges are serrated, and the thin walls are strengthened 

 by a sort of buttresses, only seen in certain ligbts. Towards and 

 over the " ears" the ridges are so modified as to leave hexagonal 

 depressed spaces ; while in one spot, beneath which the enclosed 

 larva bears its eyes, the shell is left beautifully smooth and trans- 

 parent. This creature, then, with its " toughened glass " window, 

 is remarkably well protected ; — in storms or any danger he has only 

 to shut up his shells, hold on by his antenna?, and keep a good 

 look out. 



EXPLANATION OP PLATE XIII (Upper Part). 



Fig. 1. — Larva of Lepas australis (after Darwin). 

 Fig. 2. — 5 Larva of Lepas pectinata. 



