REPORT ON THE CRUSTACEA MACRTJRA. 353 



Development of Sergestes. 



Our knowledge of the development of this genus is still imperfect, although it 

 is the result of the examination nf numerous specimens obtained at different times 

 by different persons, of their comparison with one another, and of deductions drawn 

 from the general appearances of the animals and the relative proportions of their parts. 



As in all the species of this order, the brephalos, or the organism as it first issues from 

 the ovum, is unknown. The ovum is most probably deposited in the sea and hatched in 

 the warmer waters of the ocean. 



In the genus Leucifer Professor Brooks has fortunately been enabled to procure some 

 ova, which he found not united to the parent, as they generally are in the higher 

 Crustacea, by means of organic tissue attaching them to the pleopoda, nor carried in 

 pouches, or in ovisacs, as in Mysis, Gammarus, &c, but rather as if they were entangled 

 amongst the pereiopoda and cohering to one another. 



The youngest form that we know is that shown in the annexed figure (fig. 49) taken 

 from the drawing of Dr. v. Willemoes Suhm. 



" Zoea of Sergestes, x 244 1 nat. size, just hatched, H ^, 28 August, 1875, in the 10 

 of Latitude, on the passage from Hilo to Tahiti. 



" Length of the abdomen, 

 Length of the carapace, without spines, 

 Length, entire, 



Greatest breadth of the carapace, 

 Length of a 1 , 



21 mm. 

 0-35 „ 

 0-56 „ 

 0-38 „ 

 0-7 „ 



" First antennas four-jointed at the base, which disappears later. 



" oc. The early formation of the eye ; right and left of the deejily situated Nauplius 

 eye. Mandibles apparent ; first maxillae and labium not visible and perhaps not yet 

 formed, although the palpus of the first maxilla is very distinct, as also the second 

 maxilla, maxilliped, and gnathopod. When the yolk mass in the interior does not hide 

 anvthing one observes some graindike substance with bright bladders between. The 

 posterior spine of the carapace does not go exactly straight backwards but upwards. 

 The rostrum is certainly wanting." 



The above are the notes made regarding this specimen by Dr. v. Willemoes Suhm, 

 after whom I have named it. 



Elaphocai 'is suhmi. 



It differs from all other specimens at this stage in the absence of a rostrum, which is 

 generally so persistent a feature. The great frontodateral spinous processes are remark- 

 able for their length, and still more for being biramose, the division commencing at 



1 From which our figure, for convenience, is reduced one-third, or to about 163"3. 

 (ZOOL. CHALL. EXP. — PART LII. — 1886.) Fff 45 



