44 1)E. G. C. BOURNE ON THE KANINIDiE : 
oh the " epistoine." But the French naturalist, usually so exact in the 
definition and use o£ anatomical terms, goes sadly astray in the application 
of the terms under discussion, and has thus introduced a confusion which 
has persisted in carcinological literature down to the present day. Thus in 
vol. ii. p. 170 o£ the ' Histoire Naturelle des Grustaces'' we find it stated of 
IJromia, "I'epistome est triangulaire," but clearly the triangular sternal 
element here referred to is the antenmdart/ sternum (see infra, p. 50). Jn 
the same place he says, " le cadre buccal est a peu pres carre," and it is clear 
from an examination in this region in Jhomia, that the "cadre buccal" 
is the combined antennary and mandibular sternum, that is, by h's own 
definition, the epistome. Again in a-oI. ii. p. 97 we find it stated of the 
Oxystomatous crabs, " le cadre buccal est tout-a-f ait triangulaire," and on 
p. 102 of the Calappidse, "il n'y a point d'ejiistome distinct." But a study 
of these crabs shows that the triangular "cadre buccal'' is chiefly made up 
of the antennary slernum, i.e., it is the epistome, which is said to be absent ! 
Among more recent authors, Oalman (23, p. 257) writes : " the antennal 
sternum is mainly represented by the epistome, a plate of varying shiipe 
lying between the labrum and the bases of the antennae," and further on 
"the buccal frame is more or less distinctly delimited by the epistome 
itself or by a transverse ridge which divides the epistome into two parts, 
the epistome proper and the endostome or palate." He does not, with 
Huxley, recognise the inclusion of the mandibular sternum, but there can be 
no doubt that Caiman identifies the greater part of the " epistome " with the 
antennary sternum. A little further on the same author makes the following 
statement : "In all the Brjichyura the rostrum or frontal plates ends down- 
wards in the middle line a process which unites in front of the ophthalmic 
and antennular sterna with the epistome and separates from one another 
the basal segments of the antennules." This represents accurately enough 
the prevailing opinion on the subject, and indicates quite clearly that the 
antennular}' sternum is not to be regarded as a component part of the 
"epistome." But, whilst this part of the statement is accurate, the i-e- 
maining part is most inaccurate, for an examination of a large number of 
crabs belonging to diverse families shows that, with very few exceptions, the 
downward process of the front or rostrum does not unite with the antennary 
sternum, that is Yifith the epistome, but with the antennulary sternum. The 
fact is so obvious that it is difficult to understand how the error originated, 
the more so because Milne Edwards, however obscure he may have been on 
the subject of the epistome, is quite definite and exact on this point. " Le 
front se prolonge au-dessus de I'annean qui porte les yeux. Dans le jeune 
age, cet anneau reste a decouvort anterieurement, et les yeux ne sont pas 
leges dans des cavites orbitaires completes ; niais, plus tard, la partie 
inferieure du front se reunit, sur la ligne mediane, a une prolongement de 
