472 R. ETHERIDGE ON SPECIES OF ANTHRAPALEMON 
in two strong incurved spines; anterior margin concave, produced 
into a central rostrum or mucro; posterior margin also concave, 
but in an opposite direction to the anterior. Surface divided into 
two very unequal parts by a wide and well-marked cervical groove, 
the anterior portion being much the smaller. The lateral margins 
anterior to the cervical groove are finely and obtusely serrate, and 
terminate forwards in small short spines; posterior to the groove 
the margins become thickened and are horizontally crenulate, the 
crenulations having their convexities directed backwards. ‘The 
central line of the carapace is occupied by a thickened dorsal ridge 
continuous from the posterior margin forwards to the cervical 
groove, and thence connected with the anterior mucro.  Pro- 
ceeding from the posterior incuryed spines of the carapace are two 
almost median-lateral thickened ridges, which gradually curve 
outwards as they approach the cervical groove, where they ter- 
minate. All the ridges present on the carapace are similarly 
ornamented to the posterior portion of the lateral margins. The 
cervical groove appears to have a branch on each side directed 
towards the antero-lateral spines. The rostrum or mucro is tapering 
and pointed. On each side of the central ridge on that portion of 
the carapace anterior to the cervical groove are two circular blunt 
eminences, abutting on the anterior branch of the former. Body- 
segments and appendages unknown. 
Obs.. A very marked appearance is given to this fossil by the 
strongly developed carapace-ridges, with their crenulated striz, the 
elongated and incurved posterior angles, and the deeply concave pos- 
terior margin of the carapace. Again, the broad and deep cervical 
groove is another feature to be noted, quite interrupting, as it does, 
the continuity of the central carapace-ridge with the rostrum; it 
must, however, be remembered that perhaps the preservation of the 
integument would considerably lessen this appearance. 
Omitting from consideration the presence of the cervical groove 
and rostrum, the general aspect of this species is very Dithyro- 
caroid ; so much so, that until I had carefully studied the specimens, 
I was inclined to refer them to that genus. 
In no case is the true integument preserved; but the substance 
of the crustacean is converted into a soft white pulverulent sub- 
stance, requiring the application of some mucilaginous material for 
its preservation in the cabinet. 
The average size of A. Macconochii is about eight lines from the 
tip of the rostrum to a line drawn between the two posterior 
angles, and the breadth five lines; one specimen measures ten 
lines by seven, and there are the mutilated remains of still larger 
individuals. ‘The smallest example is three and a half lines long by 
two and a half broad, and very well illustrates the complete dissimi- 
larity of the species from the preceding, A. Woodward, conclusively 
showing that one cannot be assumed to be the young or immature 
form of the other. There appears to be little variation amongst the 
specimens in the Survey collection ; and, strange to say, notwith- 
standing the number of individuals on some pieces of cement-stone 
