534 BULLETIN 54, UNITED 8TATES NATIONAL MUSEUM. 



lateral portions of fifth segment end in a sharp crest, and there is no 

 'shield.' The sixth segment is very long; it narrows posteriorly, 

 has a fleshy median keel and only slightly developed lateral por- 

 tions. The seventh segment is short, fleshy, about as wide as sixth 





PlG. 579. STEGOPHRYXfS HYPTIUS (AFTF.R THOMPSON). (I, DoKSAI. VIKW OK AIU'I.T MALE. X 12. 



b, VENTRAL SIDE OF HEAD OP SAME, x 22. c, VENTRAL VIEW OF HEAD OF CRYPTONISCID. x 110. 

 d, CRYPTONISCID FROM YOUNG FEMALE (LATERAL VIEW), x 58. e, PLEOPOD OF THIRD ABDOMINAL 



SEGMENT OF CRYPTONISCID. X 70. /, MUSCULATURE OF ONE OF FIRST FOUR PEREIOPODA (ADULT 



FEMALE), x 20. g, MUSCULATURE OF ONE OF SIXTH OR SEVENTH PEREIOPODA OF FEMALE, x 20. 

 h, MUSCULATURE OF PEREIOPOD. x 40. i, DORSAL VIEW OF LARVAL FEMALE, x 12. j, VENTRAL 



VIEW OF SAME. X 6}. 



and similar to it, except that it is not keeled. Ventral surface of 

 thoracic segment fleshy, posterior borders of sixth and seventh modi- 

 fied into complex elevated keels. Pereiopoda of the sixth and seventh 

 segments are alike and quite simple in construction; those of the other 



