458 U.S. NATIONAL MUSEUM BULLETIN 271 



posteriorwards and at right angles to anterior margin, posterodorsal 

 excavation almost right-angular, articles 2 and 3 of antenna 1 even if 

 shortened always together as long as article 1, distal tooth of latter if 

 present short and hook-like 3 



3. Telson entire 4 



Telson cleft Syrrhoites 



4. Palms of gnathopods bearing one or two serrate spines, coxa 4 adze-shaped, 



tooth distinctly posteroventral Bruzelia 



Palms of gnathopods with 4 nonserrate blunt spines, coxa 4 rectangular and 

 bearing midposterior cusp Stephobruzelia, new genus 



5. Both telson and peduncle of uropod 3 very short and subequal in length, 



mandibular palp extremely stout (fig. 165e) Synopia 



Telson elongate, twice as long as peduncle of uropod 3 even when peduncle 

 elongate, mandibular palp slender (figs. 166d,e) 6 



6. Coxa 3 strongly expanded distally, some portion of distal half at least twice 



as broad as proximal end, expansion directed posteriorly, posterodorsal 

 margin strongly excavate, coxa 4 much smaller than 3, comma-shaped and 

 usually with less than half as much surface area as coxa 3 7 



Coxa 3 rectangular or quadrate, scarcely expanded distally, occasionally 

 with anteroventral corner attenuated only, posterior margin nearly parallel 

 with anterior margin, coxa 4 almost as long as 3, its surface area scarcely 

 smaller than that of coxa 3, coxa 4 adze-shaped or chisel-shaped ... 9 



Coxa 3 rectangular or subquadrate, scarcely expanded distally, coxa 4 



noticeably shorter than 3 and weakly comma-shaped 



some species of Tiron 



7. Article 6 of gnathopods linear, slender, rectangular, simple, lacking strong 



serrate spines Pseudotiron 



Article 6 of gnathopods, if simple not linear or rectangular, either ovate and 

 tumid or bearing distinct transverse palms, palms bearing one or two 

 serrate spines 8 



8. Telson cleft more than halfway, palms of gnathopods transverse . Syrrhoe 

 Telson cleft less than 20%, palms of gnathopods oblique or indistinct. 



Ileraustroe, new genus 



9. Article 6 of both gnathopods linear, slender, rectangular, simple, lacking 



strong serrate spines Tiron 



Article 6 of gnathopod 1 tumid but article 6 of gnathopod 2 perfectly linear 



and rectangular . . Syrrhoe fimbriatus ^ Stebbing and Robertson, 1891 

 Article 6 of both gnathopods, if simple not linear or rectangular, either ovate 



and tumid or bearing transverse palms, palms bearing one or two serrate 



spines 10 



10. Palms of gnathopods transverse, each bearing one very large spine giving 



chelate appearance to palms Garosyrrhoe 



Palms of gnathopods oblique or obsolescent, bearing one or two serrate 



spines but not appearing chelate Austrosyrrhoe 



Currently assigned to Austrosyrrhoe. 



Genera of Synopiidae 



Austrosyrrhoe K. H. Barnard 



Austrosyrrhoe K. H. Barnard, 1925. 



