664 CLASS X. 
observed by him might really be the larva of some decapod. KRoEYER 
(Tidsskr. 111. 1841, pp. 503—534) 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 antenne 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. Goopsir and KroEYER have adopted some new genera 
in this small family: Zewcon Kroryrr, Bodotria Goopsir and Alauna 
Goopsir, which last genus, however, KROEYER characterizes differently. 
See hereon Tidsshrift, Ny Rackke, 11. 1846, pp. 123—211. 
ORDER X. Decapoda. 
T'wo compound eyes, placed on a petiole moveable, biarticulate. 
Antenne four. Carapace large, covering head, thorax and anterior 
abdomen. Branchiz 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 in.portant +o man on account of the quantity of edible species. 
Section I. Macvoura. 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. 
Antenne long, the middle exsert, terminated by two or three 
setaceous filaments. Vulve 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 antenne inserted mostly 
above the lateral, more rarely in the same horizontal plane as lateral. 
