THE SPIDER CRABS OF AMERICA 13 



Genus STENORYNCHUS Lamarck 



Leptopodia Leach, ZooI. Misc., vol. 2, 1815, p. 15; type, L. sagillaria (Leach, 

 1814)=5. seticornis (Herbst, 1788). Not Leptopodia Leach, Edin. Encyc, 

 vol. 7, 1814, p. 431, which is a synonym of Macropodia Leach, 1814. 



Stenorynchus Lamarck, Hist. Nat. Anim. sans Vert., vol. 5, 1818, p. 236 

 (part); not Stenorhynchus Latreille, 1825, nor Stenorynchus Milne Edwards, 

 1834.— Rathbun, Proc. Biol. Soc. Washington, vol. 11, 1897, p. 158; 

 type specified, S. seticornis (Herbst, 1788). 



Carapace triangular, longer than broad, smooth. Rostrum very 

 slender, flattened, longer than the carapace, its lateral margins spinu- 

 liferous. Orbits not defined; postorbital spine small. Eyes short, 

 not retractile. Basal article of antenna very slender; flagellum con- 

 cealed beneath the rostrum. Epistome very large. Ischium of 

 external maxillipeds produced at its antero-internal angle; merus 

 somewhat obcordate, bearing the next article at its external angle. 

 Abdomen in male six-segmented, in female five-segmented. Cheli- 

 peds long and slender, with merus, carpus, and palm subcylindrical ; 

 fingers much shorter than palm, inner margins dentate. Ambulatory 

 legs extremely long and slender, especially the dactyli. All the legs 

 spinuliferous. 



Inhabits both coasts of middle America; also the islands of the east- 

 ern Atlantic, and the Atlantic coast of northwest Africa. 



Analogous species on opposite sides of the continent: seticornis 

 (Atlantic) ; dehilis (Pacific) . 



KEY TO THE 3PECIE3 OF THE GENUS 3TENORYNCHU3 



A'. No spine at end of basal article of antenna. Rostrum very long, up to two 

 and a half times as long as remainder of carapace seticornis, p. 13. 



A'. A small spine at end of basal article of antenna. Rostrum usually about as 

 long as remainder of carapace, in the old longer debilis, p. 18. 



STENORYNCHUS SETICORNIS (Herbst) '3 



ARROW-CRAB; ARANiA DEL MAR 



Plates 2 and 3 



Oost-Indische Zee-Krabbe Slabber, Natuurkundige Verlustigingen, Haarlem, 

 1778, p. 162, pi. 18, fig. 2. 



Araiia Parra, Descripcion de diferentes piezas de historia natural, 1787, 

 p. 162, pi. 56, fig. 3. 



Cancer seticornis Herbst, Natur. Krabben u. Krebse, vol. 1, 1788, p. 229, 

 pi. 16, fig. 91 (after Slabber) ; vol. 3, part 3, 1803, p. 27, pi. 55, fig. 2 (Guade- 

 loupe). — Olivier, Encyc. Meth., Hist. Nat., Entom., vol. 6, 1791, p. 178. 



" The crab Cancer seticornis was described by Herbst, 1788, after Slabber, who stated that it came from the 

 East Indies. It has, however, never been found in that region. It is obviously congeneric with Steno- 

 rynchus Sagittarius (Fabricius). There are only two species in this genus of arrow-crabs. The length of 

 the chelae in Slabber's figure prevents its union with S. debilis: therefore, it is here combined with the other 

 existing form, Sagittarius, which is widely distributed in the Atlantic Ocean. This is in line with the pro- 

 cedure of Herbst, who, in 1803, united the West Indian form (he had then a specimen from Guadeloupe) 

 with that of Slabber. 



5487— 25t 3 



