382 



THE VOYAGE OF H.M.S. CHALLENGER. 



" Otoliths present. 



" H. \; about 35 times nat. size. 



" Taken on the voyage from Hilo to Tahiti, hit. 5° 0' N. 



" Branchiae still wanting. 



" Of the lateral spines of the carapace one is still to be seen. 



The preceding figure (fig. 52) is reduced one-third from Dr. v. Willemoes Suhm's draw- 

 ing, and represents what he calls the fourth or Zmc«/er-stage,orthat immediately preceding 

 the adult form. It corresponds closely with that which I have just described as Mastigopus 

 suhmi, and which is represented on PL LXVI. fig. 2. It differs, however, in some details 

 of more or less importance; Suhm's specimen, for instance, is 3 "8 mm. long, while mine is 

 5 mm., and the carapace is rounder in Suhm's than in that which I have drawn. He 

 represents the ophthalmopoda as being more fungiform and the scaphocerite as beino- 

 very much longer. 



t 



Fig. 53. Oral appendages of Mastigopus crassus. ■■, First maxilla ; /, second maxilla : g, maxillipede ; /;, first gnathopod ; t, telson. 



seen laterally. 



The form of the oral appendages is shown in the annexed cuts (tig. 53). 



The second pair of gnathopoda is well shown in fig. 52, as also are the several 

 pairs of pereiopoda ; the first and second having the basis furnished with a small tuber- 

 cular process on the anterior margin, similar to that shown in Mastigopus spiniventralis 

 (PI. LXVII. fig. 4). The second and third pairs have not as yet assumed the chelate. 



