234 CRABS OF THE FAMILY PERICERIDA—RATHBUN. 
Pericera. 
A’ Carapace with strong median spines. 
BuCarapace oblong-ovate: <2. 5 sass. 5. 2c gee ee eee eee eee atlantica. 
B!Carapace triangulate: so...) hele ase see ee ee ee triangulata. 
A” Carapace without streng median spines. 
ib) Rostral horns divergent fromthe base-sssese2 22-2 == ee ee cornuta. 
BeeRostral horns divercent.at hips onlye-s 29-2 ese ae eee ae ee contigua, 
Tiarinia 
Carapace covered with prominent warty tubercles.--.....--..---.-----.-- cornigera. 
Microphrys. 
AC Rostral horns short; tlatvbened (<2. 2-22 452-5. eee oe ee eee Microphrys, sp. 
ostral horns lonp; thickened 2. =2 5. J22s esse e aap eee ee eee icornutus, 
A” Rostral 1 long, thickened b 1 
Macroceloma. 
A’ Carapace with dorsal spines besides the epibranchial and posterior spines. 
B’ Carapace subtriangular. 
C’ Carapace with four spines at summit. 
D/SRostrum strongly detlex ede. 2ea-s- ec as Oe ee septemspinosa. 
DRostrum ‘almost horizontal sss. 352 eec See eee ee eee camptocera. 
C” Carapace with spiny ridge between epibranchial spines.-...-.-.--- subparallela. 
C’” Carapace with two spines on the intestinal region.....-----.---- tenuirostra. 
Bi Carapacesubtrapezoidalis.<e25 42252. Sie ae ee ee oe eee eee ee eutheca, 
A” Carapace without dorsal spines except the epibranchial and posterior spines. 
bebipibranchialispinetw0-lobed jhe s 2a. eee eee es diplacantha. 
Bibi pibranchialspine mnotWobede ses m= sees rate trispinosa. 
Othonia. 
A Antero-lateral teeth rounded: =. 252 j2eet22= Soe ses eee eee eee aculeata. 
A” Antero-lateral teeth acute. 
BeCarapace smooth, pulbescente=.- 2s: esse ean a= ae = eee therminieri. 
iB Carapace densely, cranulous:-5 225. 22.6 222-2 see eee eee rotunda, 
B’” Carapace tuberculous. 
C’ Carapace broadest at fourth pair of teeth -....----.-.--..-.-+--.---- nicholsi. 
C” Carapace broadest at third pair of teeth. ...........----.+-..2.-- carolinensis. 
Thoe. 
Antero-lateral margin straight or a little concave ..............----.---.----puella. 
Mithrax. 
A’ Carapace with dorsal sulci. 
B’ Antero-lateral margins with spines only. 
@eCarapace longer than broad’ <2 se eseee seer ee eee Cee eee eee cinctimanus. 
@Carapace broader thandong...24- 52-2 ee ae eo ee eee forceps. 
BY” Antero-lateral margins with lobes, or lobes and spines. 
C’ Carapace much broader than long; lateral margins angular. 
D’ Lateral angle formed by a spine hooked forward -....-.-----..-denticulatus. 
De ateral angle.formed bya lobes) caeaseetee see eee eee coronatus. 
C” Carapace slightly broader than long; lateral margin rounded. 
D’ Lateral margin with three large lobes followed by a spine.--..---- nodosus. 
D” Lateral margin with four small lobes =2c2-. s222 +24. ee eee eee sculptus. 
