THE SPIDER CRABS OF AMERICA 511 



KEY TO THE AMERICAN GENERA AND SUBGENERA OF THE FAMILY PARTHENOPIDAE 



A'. Carapace not laterally expanded over the ambulatory legs. 

 B'. Carapace tuberculate or eroded. 



C. Basal antennal article short, not reaching front. Merus of cheliped 



not thigh-shaped Parthenope, p. 511. 



D". Chelipeds more than twice as long as carapace. 



E'. Carapace ovate-pentagonal, surface little carinate in adult. 



Subgenus Parthenope, p. 513. 

 E2. Carapace carinate or tuberculate, broadly triangular, with more or 



less rounded sides Subgenus Platylambrus, p. 516. 



D^. Chelipeds less than twice as long as carapace, stout and contorted. 



Subgenus Pseudolambrus, p. 528. 

 C-. Basal antennal article rather long, reaching or nearly reaching orbital 

 hiatus. 

 D^ Merus of cheliped thigh-shaped, tapering distally. Manus more 



slender Thyrolambrus, p. 531. 



D-. Merus subtriangular in cross-section, not tapering distally. Manus 



stouter Tutankhamen, p. 530. 



B2. Carapace smooth, except for a few strong spines. 



C^ Efferent branchial channels opening at sides of endostome (as is cus- 

 tomary in the Oxyrhyncha). 

 Di. Carapace high, without a strong lateral spine. _Solenolambrus, p. 534. 

 D2. Carapace depressed, with a strong lateral spine. .Leiolambrus, p. 543. 

 C^. Efferent branchial channels opening at middle of endostome, as in 



the Oxystomata Mesorhoea, p. 546. 



A^. Carapace more or less expanded to form a vault in which the ambulatory 

 legs are concealed. 

 BK Carapace oval, expanded laterally but not posteriorly. No ridge on 



pterygostomian region Aethra, p. 550. 



B^. Carapace subtriangular or pentagonal. 



C. Carapace greatly expanded both laterally and posteriorly. Pterygos- 

 tomian region smooth, not ridged Cryptopodia, p. 553. 



C^. Carapace expanded laterally but not posteriorly. Pterygostomian and 

 subhepatic regions traversed by a granulate or crenulate ridge. 



Heterocrypta, p. 554. 

 Genus PARTHENOPE Weber 



Parthenope Wkber, Nomenclator entomologicus, 1795, p. 92; type, P. 



longimanus (Linnaeus) .^ — R.^thbun, Proc. Biol. Soc. Washington, vol. 17, 



1904, p. 171. Not Parthenope Fabricius, Entom. Syst., Suppl., 1798, 



p. 315. 

 Lambrus Leach, Trans. Linn. Soc. London, vol. 11, 1815, pp. 308 and 310; 



type, L. longimanus (Linnaeus). — Alcock, Journ. Asiat. Soc. Bengal, 



vol. 64, 1895, p. 259, and synonymy. 



Carapace either broadly triangular or ovate-pentagonal with short, 

 pointed front. Surface granular, tubercular, or spiny. Eyes in- 

 closed in distinct orbits, with a suture above and hiatus below, the 

 hiatus occupied by the second joint of antennal peduncle. The 

 antennules fold obliquely. Antennae small; their basal joint, which 

 is extremely short and does not reach the front, is wedged in between 

 the antennulary fossa and the large lobe that constitutes floor of 

 orbit. Buccal frame usually quadrangular, sometimes a Uttle nar- 



