664 CLASS x. 



observed by him might really be the larva of some decapod. KEOEYER 

 (Tidsskr. in. 1841, pp. 503534) has refuted this, having found other 

 species of this form, and females with eggs in a sac beneath the abdomen. 

 Cuma is thus an adult animal. It has no eyes, almost the form of a 

 long-tailed decapod, but five thoracic rings are not covered by the shell. 

 The superior antennae are short, the inferior in the female very short and 

 rudimentary, in the male long. The feet have no shears. These animals 

 resemble the Caridina, but perhaps better still might they be referred to 

 the stomapods. GOODSIR and KROETER have adopted some new genera 

 in this small family: Leucon KROEYER, Bodotria GOODSIR and Alauna 

 GOODSIR, which last genus, however, KROEYER characterizes differently. 

 See hereon TidssJcrift, Ny Raekke, n. 1846, pp. 123 211. 



ORDEE X. Decapoda. 



Two compound eyes, placed on a petiole moveable, biarticulate. 

 Antennae four. Carapace large, covering head, thorax and anterior 

 abdomen. Branchiae adhering to the base of the posterior maxilli- 

 form feet and of the feet of trunk, pyramidal, covered by the sides 

 of the shield. Mostly three pairs of maxilliform feet, in a few only 

 two pairs. Feet of trunk not changed, almost always in five pairs, 

 in some six. Mandibles almost always furnished with a palp. 



Most crustaceans of this order have a very hard covering, and to it, 

 with the exception of the Limuli, the largest species belong : but 

 there are many small ones also. It is the most numerous and the 

 most important to man on account of the quantity of edible species. 



Section I. Macroura. Post-abdomen large, often longer than 

 cephalothorax. Penultimate segment with lateral appendages form- 

 ing with the last segment a terminal pinna of the tail, mostly 

 flabelliform. 



Antennae long, the middle exsert, terminated by two or three 

 setaceous filaments. Vulvae situated in the first joint of the third 

 pair of feet. 



The third pair of foot-jaws are elongate, whilst on the contrary 

 they are broad in the following division and cover the oral apparatus. 

 The caudal feet are mostly more developed than in the following 

 division, and serve for swimming. The shell is not so thick as in 

 the Brachyura and at the same time less hard. 



Family XXVII. Caridina. Middle antennae inserted mostly 

 above the lateral, more rarely in the same horizontal plane as lateral. 



