THE SPIDER CRABS OF AMERICA 337 



G'. Rostrum small. Carapace ovate, usually broader than long. 



Orbits not tubular. 



H'. Lateral margins of carapace laminiform, coarsely dentate. 



Carapace broadly triangular-ovate. Chelipeds and legs 



cristate above. Orbital margin not incised, bearing a 



preocular spine and a postocular tooth. Anaptychus, p. 377. 



H^'. Lateral margins armed with four, or three, spines or lobes 



behind orbit. Legs spinous. Orbital margin spinous or 



tuberculous Mithrax, p. 379. 



G*. Rostrum of good size, usually with two strong horns. 



H'. Lateral margin of carapace armed with a series of strong 

 spines. Basal antennal article very broad. 

 J'. Basal antennal article quadridentate. Postocular tooth 

 large, quadrangular, armed with two teeth or spines. 



Coelocerus, p. 446. 



J^ Basal antennal article armed with fewer than four spines 



or teeth. Postocular tooth of moderate size, triangular, 



armed with only one spine Stenocionops, p. 448. 



H*. Lateral margin of carapace not armed with a series of strong 

 spines, but with a spine, usually strong, or a tubercle, at 

 the lateral angle of the carapace. 

 J'. Orbits tubular, strongly projecting; basal antennal article 



very broad Macrocoeloma, p. 463. 



P. Orbits little projecting, basal antennal article moderately 

 broad, armed with a prominent spine at antero-external 



angle Microphrys, p. 488. 



A'. Eyes partially protected by a huge hornlike supraocular spine; orbit unpro- 

 tected below. Exognath of outer maxilliped with a falciform basal pro- 

 longation which is bent around forward and lodged in a groove of the 

 ischium of the endognath, while the merus is extended in a similar way 

 backward into the ischium Tyche, p. 507. 



Genus MAIOPSIS Faxon 



Maiopsis Faxon, Bull. Mus. Comp. Zool., vol. 24, 1893, p. 150; type, M. 

 panamensis Faxon; Mem. Mus. Comp. Zool., vol. 18, 1895, p. 11. 



Carapace sub triangular, as broad as long, spinose; rostrum pro- 

 duced into 2 divergent horns with an accessory spine on outer mar- 

 gins; interorbital space broad. Eyes small, eyestalks slender, 

 retractile within orbits. Orbits large, with a forward aspect, incom- 

 plete below, upper margin prominent, w4th 2 deep fissures, and 

 supraocular spines. Epistome short. Basal segment of antennae 

 very broad, 3 prominent spines on anterior margin; flagellum widely 

 separated from cavity of orbit by a broad process of basal segment. 

 Merus of outer maxillipeds notched at antero-internal angle. Cheli- 

 peds and legs of moderate length. Carpus of chelipeds elongate, not 

 carinate; chela elongate, slender, fingers canaliculate within, but not 

 spoon-shaped at tips, prehensile edges meeting throughout most of 

 their length, not distinctly toothed. xYmbulatory legs spinose. 

 Abdomen of male T-jointed, terminal joint short and broad. (Faxon.) 



Contains but one species. 



