678 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXVII. 



and five pairs of incubatory lamellte, onh' four pairs of legs and of 

 incubator}" lamella? being- true of Branchiophryxus, and in having- a 

 single pair of pleopoda, which are altogether wanting in that genus. 

 It difl'ers from N<)t<>j>/n'y,i'us Sars in the form of the abdomen and head 

 and in having five pairs of incubacory lamellae instead of a single pair. 

 It diti'ers from Axj)!<Joj)hrij,n(s Sars in the form of the head and abdo- 

 men of the female, and in having no trace of segmentation or append- 

 asres to the abdomen of the male. 



Fig. 30. — ZoNOPHRYXUs retrodens, new species, a, 



DORSAL VIEW; /), VENTRAL VIEW. X 4. 



ZONOPHRYXUS RETRODENS Richardson, new species. 



Body of female (tig. HO) rather quadrangular in shape, with only 

 faint traces of segmentation on the dorsal surface. Dorsal surface 



very convex, with no distinct 

 ])Oundary between the three 

 chief divisions of the body, 

 the head, thorax, and al)do- 

 men being continuously one. 

 On the ventral side a l)order 

 surrounds the entire body, 

 and is wider in the cephalic 

 region. (Fig. 31.) 



The cephalic part projects 

 in front as a broadly rounded 

 area or border. On either side 

 of the body on the anterior 

 half of the body, the lateral 

 border is incised with three small indentations, marking off the head 

 from the first thoracic segment, the second from the 

 first, and the third from the second. Five indistinct 

 lines on the dorsal surface of the anterior half of the 

 body mark otf the lunid from the thorax and outline the 

 first four thoracic segments. The pos- 

 terior half of the body shows no trace of 

 segmentation on the dorsal surface. The 

 posterior margin of the l)order at the 

 terminal part of the body is produced in 

 !> triangularly-shaped processes. These 

 processes are arranged four on either 

 side of a median one, and undoubtedly indicate the 

 five coalesced a})dominal segments. 



The legs are in five pairs and are confined to the 

 anterior half of the body on the ventral side. 

 The incubatory lamella^ (fig. 82) consist of five pairs of plates, meet- 

 ing in the median ventral line. The fifth pair overlap the second, third, 

 and fourth pairs. 



Fig. 31.— Maxil- 

 liped of zono- 

 phryxus re- 

 TRODENS. <14i. 



Fig. 32.— First la- 



MELL.\ OF MARSr- 

 PIUM OP ZONO- 

 PHRYXUS RETRO- 

 DENS. X Hi. 



