906 THE VOYAGE OF H.M.S. CHALLENGER. 



margin of the scaphocerite, as there is in fig. 3, but corresponds in this part more nearly 

 with that shown in the younger form of figs. 1 and 4. 



In fig. 4 a tooth is shown as standing on the basis of the third appendage ; it ought 

 however to be mentioned that this tooth is absent from the leg upon the opposite side of 

 the animal in the same pair. 



The next specimen that marks an advance in development is one from the Pacific, 

 in which four pairs of appendages — two gnathopoda and two pereiopoda — are well 

 developed. It is 10'5 mm. (0'4 in.) in length, and, as in all the Pacific specimens, 

 the small rostral tooth is visible in the centre of the frontal margin. The rest of the 

 animal corresponds in most of its details with the forms described later, excepting that 

 the telson has lost its foliaceous character and become more robust, it tapers to the 

 extremity, and terminates in two small points as shown in PI. CXLVII. fig. lz. 



In the month of February 1875, between the Philippine Islands and New Guinea, 

 a specimen (fig. 75) was taken which has five pairs of appendages attached. It is 

 11 mm. (0 - 4 in.) long. The appendages are all developed on the same typical plan as in 

 the preceding specimen ; the small rostral tooth is present, and the only change beyond 

 the addition of a pair of pereiopoda is that the telson has sent out at each point at its 

 extremity two long and slender teeth. 



Amphion reynaudii, Milne-Edwards (PI. CXLVII. figs. 1, 2). 



Amphion Reinavdii, Milne-Edwards, Ann. Soc. Entom. France, torn. i. p. 336, pi. xii. figs. 1-10, 

 1832. 

 „ Reynaudii, Milne- Edwards, Hist. Nat. Crust., torn. ii. p. 489, pi. xviii. figs. 8, 9, 1837. 



This species was founded upon a specimen taken by M. Keynaud at the surface 

 {en haute mer) of the Indian Ocean, and described and figured by Professor Milne- 

 Edwards in the works above quoted. It was about one inch in length, and corresponds 

 closely with the Challenger specimens, which approach it in size, and in the number of the 

 pereiopoda, but it appears to be a little more advanced in development, more especially 

 in the condition of the pleopoda, which are present in the form of biramose hairless 

 buds. 



The Challenger specimens have six well-developed pairs of appendages attached to the 

 pereion, and like all the specimens taken in the Pacific, have a small rostral tooth attached 

 to the frontal margin of the carapace, but which is hidden in the figure by the projection 

 of the metope. In Milne-Edwards' figures this rostral tooth is not shown, probably 

 owing to its concealment by the metope, or perhaps from the specimen having been 

 examined with only a low power. 



In our specimens the frontal margin of the carapace is slightly waved in a line across 

 from side to side, with a minute rostral tooth in the median line ; it is continued on each 



