62 A HISTORY OF RECENT CRUSTACEA 
If the tiny young of the Crustacea attack and destroy 
one another, it is not for want of innumerable other enemies 
fitted to keep their numbers in check. As far as the 
timidity of human experience can decide, the Crustacea in 
general, though by no means particular as to the food they 
consume, invite rapacity by the agreeable quality of the 
food they supply. The enormous spines of the very young 
and the strong armature of the adults have probably been 
called into existence in consequence. Where these are 
wanting or inadequate, the life of the species has been 
protected by extreme fertility. In Geryon quinquedens, 
Smith, for example, it has been computed that one speci- 
men was carrying no less than forty-seven thousand eggs, 
and there are other species reckoned to be at least twice as 
prolific. 
To the extensive genus Xantho Bell assigns three 
British species, naming them florida, rivulosa, and tuber- 
culata. But, Montagu’s jloridus having lapsed as a syn- 
onym, the first of the three should be named Xantho 
incisus, Leach. The second, on Bell’s own showing, ought 
to be called Xantho hydrophilus (Herbst), and of this 
Couch’s tuberculata is now held to be a variety. 
Ozius, Milne-Edwards, 1854, was a genus established 
to receive certain species found in the Indian and Austra- 
‘lan waters. The name had been given much earlier by 
Dr. Leach, but without published description. It presents 
a peculiarity by help of which the large family of the 
Cancride is divided into two sections. The space between 
the front margin of the buccal frame and the mouth itself 
was called by Milne-Edwards the prelabial space. By 
English writers it is called the endostome or palate. In 
Cancer, Xantho, and many other genera, this endostome is 
without distinct longitudinal ridges defining the apertures 
of the efferent branchial channels, whereas in Ozius, Pilum- 
nus, Hriphia, and others, it has these ridges. 
Pseudozius, Dana, 1851, is, as the name implies, a 
genus that might be mistaken for Ozius, but the crests of 
the endostome do not quite reach the upper margin of the 
buccal frame. In 1881 the species Pseudozius Mellissa 
