284 



MR. A. GARRETT ON THE TERRESTRIAL [Mar. 1, 



clearly seen where they are encased in the skin. The tips of all the 

 digits are free, including digit iii., which has its tip free and projec- 

 ting beyond the wing-fold. On removing the skin and examining 

 the skeleton, phalanx 1 is distinct, then a rod of cartilage extends 

 to the tip of the projecting fold of skin {a, fig. 4). This rod of carti- 



Fig. 1. Phalanx 1 and the vestigial cartilage of digit iii., adult Ostrich. Ph. 1, 

 1st phalanx ; Ph. 2, 2nd phalanx ; r, vestigial cartilaginous rod ; c, 

 connective tissue. 



Fig. 2. Phalanx of digit in. of another adult Ostrich, showing Ph. 2 ankylosed. 



Fig. 3. The distal part of digit iii. in the manus of the embryo (fig. 4). 



Fig. 4. Ventral view of left manus of embryo, a, free tip of digit in. 



lage probably represents the remaining phalanges of the digit, which 

 are never definitely differentiated except phalanx 2 : this is ossified 

 in the broader basal third of the rod ; in the embryo, before ossifi- 

 cation commences, the basal part is much the broadest. All this 

 points to the conclusion that this cartilaginous rod is a vestigial 

 structure, representing in addition to the second (ossified in the adult), 

 the third probably, and possibly also the fourth, phalanx of digit in. 

 (see figures 1 and 3). 



4. On the Terrestrial Mollusks of the Viti Islands. — Part II.' 

 By Andrew Garrett, of HuahinCj Society Islands. 

 (Communicated by Mr. John H. Ponsonby, F.Z.S.) 



[Received December 8, ]886.] 

 Genus Melampus, Montfort. 



1 . Melampus lutexjs, Quoy & Gaimard. 



Auricula lutea, Quoy & Gaimard, Voy. Astrol. ii. p. 163, pi. 6. 

 figs. 25-27 ; Deshayes, Lam. Hist. viii. p. 388 ; Kiister, Auric, 

 p. 39, pi. 6. figs. 1-3 ; Mousson, Jav. Moll. p. 47, pi. 5. fig. 6. 



1 See Part I., supra, p. 164. 



