160 U.S. NATIONAL MUSEUM BULLETIN 2 58 



Characteristics of some ischyrocerid genera and species. + and are positive 

 and negative signs for the characters; "2" indicates accessory flagellum 



litotes and as long as coxa 4 in Microjassa claustris, n.sp. The accessory 

 flagellum apparently is highly conservative, being of 2 articles in 

 Ischyrocerus and Jassa, of one elongated article in Microjassa and 

 being vestigial or absent in Parajassa. Unfortunately, the accessory 

 flagellum of M. claustris, n.sp., is unknown. Nevertheless, that species 

 is better placed in Microjassa than in the other genera where changes 

 in diagnoses to permit shortened first coxae would be needed. This 

 decision is made even though M. claustris differs from the type 

 species of Microjassa by its long coxa 5 and its well developed inner 

 plate of maxilla 1. It shares the first condition with M. litotes and 

 is intergraded by M. litotes in the second character. Both of those 

 species of Microjassa probably do not warrant generic recognition 

 at this time; that recognition would be based on the inner plate of 

 maxilla 1 as contrasted to Microjassa and on coxa 1 as contrasted to 

 Parajassa and other ischyrocerids. The two species do not stand 

 directly between Parajassa and Microjassa. Parajassas have become 

 specialized by the reduction of the accessory flagellum, whereas 

 microjassas have become specialized by the reduction in size of coxae 

 and the inner plate of maxilla 1. The two species under question 

 have (or are presumed to have) the first maxilla of Parajassa com- 

 bined with the coxae and accessory flagella of Microjassa. The assort- 

 ment of mandibular palps and maxillipeds among the genera indicates 

 a complexity which might result in nomenclatural proliferation if all 

 character differences were used at a generic level. 



Microjassa claustris, new species 



Figures 40, 41 



Diagnosis.- — Rostrum and lateral cephalic lobe projecting equally, 

 lateral lobe subfalciform and subacute; eyes large; mouthparts 



