Dr. Strahl on the Limits of the Brachyura. 301 
division of them. The Incuneata break up into the Cancrovdea, 
Grapsoidea, and Leucosia. The structure of the maxillipeds and 
respiratory apparatus, and also the position of the male sexual 
organs, are the grounds of this classification. Dana has set 
up the Corystoidea also as a peculiar type ; but these must be 
united with the Cancroidea with even more justice than the 
Thelphusine, especially as the most multifarious transitions occur 
within the Cancroidea,—as the genera Paraxanthus, Lucas, Pla- 
tycarcinus, M.-E., and Perimela, Leach, unless the last-men- 
tioned genus must be entirely removed to the Corystoidea. 
The Leucosie I consider to include only Dana’s Leucoside, 
with Dorippe and Aithusa. I separate the Calappide and Matu- 
tide from them, and unite them with the Parthenopine rejected 
from the Oxyrhyncha, whilst Oncinopus must be placed amongst 
the Liberata in the neighbourhood of Hymenosoma. This com- 
bination is justified by the agreement in the situation of the 
afferent canal of the branchial cavity and of the male sexual 
organs ; and a close affinity is also shown by the strongly keeled 
claws, of which the hands are usually long : moreover, the fore- 
head is not divided at the point of attachment of the first jomt 
of the external antenna, but this joint is merely squeezed in 
between the pterygostomium and the first jomt of the inner an- 
tenna, the other parts of it are fully moveable, and thus, as it 
were, a step is made towards the Liberata. In this section the 
Parthenopine approach nearer to the Cancroid type, and the 
Matutide and Calappide to the Leucoside type, in regard to the 
structure of the outer maxillipeds. Here belongs undoubtedly 
the genus Zebrida, Adams and White, as appears from the figure 
in the ‘ Voyage of the Samarang,’ and, with some doubt, also 
Harrovia, Adams and White, of which no inferior view is given. 
The same arguments apply to Ceratocarcinus and Gonatonotus, 
Adams and White; nevertheless Gonatonotus appears rather to 
be Cancroid so far as the form of the claws allows one to judge. 
In estimating the relations here indicated by me, both figures 
and descriptions unfortunately frequently fail one. 
The Grapsoidea are formed naturally only of those of Dana’s 
Grapsoidea which remain after the separation from them of the 
families formerly named by me as Liberata. The genus Grapsus, 
limited by the rejection of Leptograpsus, Metopograpsus, &c., 
and represented by the species Pharaonis, strigosus, Webbii, &c., 
must be removed not only out of the Grapsoidea, but even en- 
tirely out of the Brachyura, because the structure of the external 
antenn differs completely from that which prevails amongst 
the Brachyura. Grapsus, namely, has no operculum at the base 
of the external antennz, but a perforated tubercle, as in the 
Macrura, and must therefore at least be placed among the Ano- 
