324 
BRITISH ENTOMOSTRACA. 
first gave to it the name of Chon dr acanthus, from the 
cartilaginous sort of spines which cover the body. 
Cuvier, in his ‘ Regne Animal/ figures two distinct 
species, but only slightly indicates them in a note ; and 
Blainville, in his Monograph of the Lerneadae, in the 
‘ Journ. de Phys/ for 1822, describes nine more, under 
the different generic names of Lernacantha, Lernentoma, 
and Lernanthropus. None of these authors, however, 
enter into any lengthened details with regard to the struc- 
ture or habits of these curious little creatures ; but a few 
years after the publication of Blainville 5 s memoir, atten- 
tion was called to their history by Nordmann, who, in 
his ‘ Mikrog. Beitr./ 1832, has given us much very in- 
teresting and valuable information with regard to them. 
He was followed by Burmeister and Kroyer, the latter 
of whom has especially devoted his attention to the 
anatomy and physiology of several species of the family. 
Since then, Rathke has followed up these inquiries with 
great diligence, and has added much to our knowledge 
of the two sexes, as well as the internal anatomy of the 
female. 
Anatomy , 8fc. — Female . The body of these animals pre- 
sents no trace of articulations, though two or three divisions 
may in general be easily recognised, consisting of the head, 
which has in many instances a sort of neck, and the 
thorax. The abdomen is nearly quite rudimentary. The 
head is small, and generally not very distinct from the 
body. It is slightly convex and smooth dorsally, and has 
a small groove running down the centre. In many of 
the species it contracts towards its lower part, forming 
a short neck before it joins the thorax. 
The eyes are totally wanting. The antennae are only one 
pair, rather flattened generally, and very indistinctly jointed. 
Immediately beneath the antennae we see the first pair 
of foot -jaws ; small, and consisting of a short but stout 
basal joint, and a hard, curved claw or hook, by means of 
which the animal assists in fastening itself to its prey. At 
