A STUDY IN CARCINOLOGY. ' 41 
transverse to the long axis o£ the body (with the exception o£ xiii/xv and 
xiv/xv, which arei directly obliquely backwards from the middle line), are of 
110 great vertical height, and give off no offset to form a sternal canal. The 
abductor muscle- cavities are of great length and slope backwards, converging 
to a point at the postero-external angle of the thorax on either side. There 
is no mid-ventral longitudinal apodeme and the arthrophrngm xiv/xv is 
rudimentary, so there is no trace of a sella turcica. The arrangements of the 
several parts are as widely diH'erent as possible from those in Lijre'ulus or 
any other of the Raninidae. 
Though de Haan in the quotation given above (p. 33) draws a contrast 
between the Eaniiiidai and tiie Dromiacea in the matter of the " apodeiiiata 
cephalica," i.e. the pleural and sternal apodemes of intersegments v/vi-ix/x, 
tiie Raninidse show more resemblance to the Dromiacea than to the Astacura 
in this region, and the two first-named groujis differ largely from the last. 
Passing over the obvious differences due to the presence of a broad and flat 
shield-sliaped sternum in the Ilaninidas, attention may be directed to the 
ajiodemes enteiing into the composition of the anterior part of the sternal 
canal. The reader will remember that in the Astacura, of which Neplirops 
norvegicus may be taken as a convenient example, the pleural and sternal 
apodemes of the three intersegments in front of ix/x, though some are missing 
and others feebly developed, unite to carry forward the sternal canal towards 
tlie region of the mouth. In front of them both the sternal and pleural 
ajiodemes, but particularly the latter, of intersegment v/vi are very largely 
developed, and their expanded internal extremities combine to form a 
stout platform between the suboesophageal ganglion mass and the stomach, 
known to the older carcinologists as the sella turcica anterior. Huxley 
named this platform the cephalic apodeme. In Notopus and Ranina, the 
only two genera of the Raninidse in which I have been able to study 
these structures in detail, the endosternites and endopleurites of intersegment 
ix/x are normal (figs. 9, 16, & 17), the Former standing nearly vertically above 
the plastron and ending above in slightly expanded summits which are 
joined in the usual way by the anterior branches of the corresponding endo- 
pleurites. The endosternites of intersegment viii/ix are small and directed 
backwards to touch the summits of the endosternites behind them. The 
endopleurite of intersegment viii/ix is minute, is not.branched, and converges 
towards the point where endosternites viii/ix and ix/x come into contact. 
Intersegment vii/viii shows only rudimentary endosternites, but its endo- 
pleurites are fairly well developed, exhibiting a very short anterior branch 
and a posterior branch which makes connection with endosternite viii/ix. 
In intersegment vi/vii there is no recognizable endosternite, but the endo- 
pleurite is present in the form of a small incurved lamella. Intersegment 
v/vi is largely membranous, and neither endosternites nor endopleurites can 
