PRAWNS FROM LAKE TAXGAXYIKA. 429 



form, and movably nrticiilMted to the fornicr. It c:U'i-ies on the 

 tip three or four very delicate bristles, one of wliich seems to be 

 sensory in character. Tliis joint nndoul)tedly answers to the 

 outer Hagellum in tlie adult animal. Of tlie inner- llagellum not 

 the slightest trace is to be found in the present larva, wJiereas 

 in all other larva? known to me it is at least indicated by a strong 

 seta attached to the inner distal corner of the peduncle. 



The anteniue (fig. 5), like the antennula>, are each composed of 

 two sharply defined joints, the jiroximal of which forms a. 

 thickish basal part imperfectly subdivided in the middle, and 

 produced at the end inside to a short conical prominence indicating 

 the place where subsequently the fiagellum will be developed. 

 The distal joint, rejjresenting the antennal scale, is considerably 

 longer than the basal part and of narrow linear form. Its outer 

 edge is perfectly smooth and terminates in a well-marked tooth- 

 like projection, whereas the inner edge carries in its outermost 

 pai't four strong ciliated seta3 attached to as many well-marked 

 ledges and curved somewhat outwards. In most other Caridea 

 known to me the antennal scale exhibits in the earlier stages of 

 the larval period a rather different structure, its distal part being 

 nai'J'owly pi'oduced and divided l)y well-marked ti'ansvei'se sutui-es 

 into several successive joints. Of such a subdivision not the 

 slightest trace is found in the present larva, nor is the distal pait 

 of the scale produced beyond the tooth of the outer corner, this 

 tooth in other Caridean lai'vte being formed only at a much later 

 period. 



The maiidihlos (fig. ()) have the inner, or masticatory, part 

 somewhat expanded and divided l)y a slight median incision 

 into two lobes ; but neitlier of these lobes exhibits the slightest 

 trace of any armature. 



The anterior tiiaxilla' (fig. 7) are trilobate, with the outermost 

 lobe (palp) well defined as a distinct joint. The middle, or 

 masticatory, lobe is somewhat more pi'ominent than the innermost, 

 or basal lobe. All three lobes extend obliquely inwards and have 

 only very slight traces of marginal spines or setaj. 



The posterior maxillrp. (fig. 8) have the fornx of oblong oval 

 plates, the edges of which are irregularly indented or divided into 

 a number of rounded lobules. The two outermost of these lobules 

 are sei)arated by a, somewhat deeper incision, and rejjresent the 

 one the exopodal, the other the endopodal part, the remaining 

 three lobules of the inner edge representing the true masticatory 

 lobes in the adult animal. As in the anterior maxillae, only very 

 slight rudiments of setae are present on the lobules. 



The three pairs of maxillipeds (figs. 9, 10, k 11), as above stated, 

 are of a very similar structure and only differ in the relative size 

 of the endopodite. The basal part consists of two impei'fectly 

 defined segments and is a little broader and more flattened in the 

 1st pair (fig. 9) than in the other two. The endopodite forms 

 a slightly incui-ved cylindi'ic stem and gradually inci'eases in 

 length from the 1st to the 3rd pair. In the 1st pair it is 



