Dr. F. Miiller on the Metamorphosei of the Prawns. 107 



freely over two or three of the newly formed segments. Anteriorly 

 it is at first covered by the contiguous eyes (fig. 3) ; when these 

 subsequently separate, it covers the interspace and the base of 

 the ocular peduncles with a triangular process which runs out 

 into a spine reaching a length of 0'12 mill. (fig. 6). The cara- 

 pace has uo other spinil'orni processes. 



Beneath this anterior part of the carapace and the paired eyes 

 is situated the single eye ; the entire space between the origins 

 of the anterior antennse (0*1 mill.) is occupied by two large 

 ganglia which meet in the median line ; their anterior surfaces 

 are strongly convex, and over both of them the integument is 

 extended in a nearly semicircular form. From the depths of 

 the free space thus left between the ganglia and the skin a 

 clavate bacillus (" crystalline cone ") rises until it nearly reaches 

 the skin ; at its lower part it is surrounded by black pigment- 

 granules. The skin appears to me in this species to be destitute 

 of lentiform thickenings. 



The antenna still form the chief instruments of locomotion ; 

 whilst in all other Zoea (of the Stomapoda, Crabs, Porcellamt, 

 Paffuri, and the Prawns which quit the egg in the Zora-form) 

 they have nothing to do with locomotion. 



The anterior (inner) antenna (04 mill, in length) now appear 

 to be divided into four joints, the first of which occupies nearly 

 half the length ; the longest of the three strong apical bristles 

 IS nearly twice as long as the antenna. Close to the apical 

 bristles and outside of them, stand one or two delicate bacilli, 

 0*09 mill, in length ; there are one or two more of these a little 

 below the apex on the outside of the terminal joint. The pos- 

 terior (outer) antenna are now close beside the inner ones, and 

 attain only about two-thirds of their length ; their thick stem 

 shows two, their inner (anterior) branch three, and their outer 

 (posterior) branch as many as ten joints. As before, the inner 

 branch is but little shorter, although much weaker, than the 

 outer one. The outer branch has as many as ten plumose 

 bristles, of which four stand at the apex and the others at the 

 ends of the six preceding joints. 



The large tq)per lip (tig. 4 l) is very much in the form of the 

 helmet of a Prussian soldier, which has only to be imagined rather 

 broader and with its peak considerably enlarged and emarginated 

 in the middle. The helmet, of which the point is directed for- 

 wards, is immoveable, and from it muscles pass to the moveable 

 peak which covers the mouth and a part of the upper jaws. 



In the examination of the uninjured animal from below, the 

 only part of the powerful upper jaws (fig. 4 in) that is seen is a 

 long tooth with two or three points, which projects far beyond 

 the more deeply seated masticatory surface, which is beset with 



