PRAWNS FUOM LAKK TAXUANYIKA. 439 



group, even immediately at'tei' liatchiiig, I have found that these 

 pai'tvS, though more or less difteriiig in structure fi'om those in 

 the adult animal, yet at all events are functionally developed. 

 This cannot, however, by any means be said to be the case in the 

 two Zoea) here under considei'ation. On the conti-ary, it is 

 evident, both from the very imperfect structure of these parts 

 and their position in i-elation to the mouth, that they cannot 

 possibly act as true masticatory organs. The larvae, of course, in 

 these early stages are quite unable to feed in the ordinary manner, 

 and must be assumed to subsist exclusively on the nutritive yolk 

 still left within the body. It seems to be very difficult to account 

 for this anomalous case ; but a hypothesis may perhaps be set 

 forth. I suggest the possibility that in the lake there is scai'city 

 of that kind of food which would be suitable to the larvae in this 

 eai'ly period, and perhaps also the absolute absence of Cladocei-a 

 in this lake may lie explained in a similai- mannei'. In the more 

 advanced stages, when the oral parts have been more fully de- 

 veloped, the larvae in all probability feed upon the small Copepoda 

 which abound in the lake. 



EXPLANATION OF THE PLATES. 

 Pl. LVIL 



Pieceiitly hatched larva (Euzoea) of : Limnocaridiiia spinipes Chii. 



Fig. 1. Dorsal view of the larva, 



2. Same larva, viewed from left side. 



3. Anterior division of the body, viewed from the ventral face, and more 



highly magnified. The three posterior limbs on left side are not fully 

 drawn, in order to show those occurring immediately in front of them 

 more distinctly. A^, antennuhe ; A", antenna? ; oc, ocellar lobe ; H, liyjjo- 

 stome; L, anterior lip; M, mandibles; ?', posterior lip; m', anterior 

 maxilla ; m-, posterior maxilla ; Mp^-Mp'-*, maxillipeds of 1st to Sid 

 pairs. 



4. Left antennula. 



5. Left antenna. 



6. Inner part of a mandible. 



7. Anterior maxilla. 



8. Posterior maxilla. 



9. Maxilliped of 1st pair. 



10. Maxilliped of 2nd pair. 



11. Maxilliped of 3rd pair. 



12. Left half of caudal plate. 



Pl. LVIII. 



Early larval stage (Zoea) of ? CarideUa cunuingtoni Clm. 



Fig. 1. Dorsal view of the larva. 



2. Same larva, viewed from left side. 



3. Anterior division of the body, viewed from the ventral face, and more 



highly magnified. The three maxillipeds on left side are omitted in 

 order to show the maxillai more distinctly. 



4. Antennula. 



5. Antenna. 



6. Maxilliped of 1st pair. 



7. Maxilliped of 2nd pair (exopodite not fully drawn). 



8. Maxilliped of 3rd pair. 



9. Developing cheliped. 



10. Developing pereiopod. 



11. Caudal plate. 



