CYAMIDAE 



311 



Description. General outline of peraeon in dorsal view ovate. Head frequently 

 with a distinct notch or groove where it is joined with 1st segment, tapering anteriorly 

 in 6*, in $ more parallel-sided. Segment 1 gibbous laterally, more so in <$ than in ?, the 

 antero-inferior angle pointed, more prominent in ? than in 6*. Segment 2 with postero- 

 lateral angle forming a forwardly 



6. 



directed hooked process in both 

 sexes. Segments 3 and 4 bluntly 

 produced at postero-lateral angles. 

 Segment 7 subtriangular, broader 

 than long, hind margin straight. 



On ventral surface in $ a pair of 

 blunt inwardly directed processes on 

 segment 5 and also behind them a 

 pair of pointed tubercles, on segment 

 6 two pairs of pointed tubercles, and 

 on segment 7 one pair of pointed 

 tubercles; in $ only one pair of 

 tubercles, much smaller than in ?, on 

 each of segments 5, 6 and 7. 



Antenna 1 , ist-3rd joints subequal, 

 and subequal to head (excluding seg- 

 ment 1). Antenna 2 much shorter 

 than istjoint of antenna 2. Maxilliped 

 in a juvenile 5 mm. long with fully- 

 developed palp. 



Gnathopod 1, 5th joint sub- 

 quadrangular in S, with a rounded 

 Fig. 172. Paracyamus erratum (R. de V.). a. Dorsal view tooth followed by a notch near hinge ; 

 of <J. A Branchia adult <J. c Branchia juv. 4-5 mm. m ? Q the inner j n onl 



</. Branchia?. e. Gnathopod 2 c?. /. Gnathopod 2?. £. Ventral .... , „ 



view of peraeon segments 5-7 ?, with proximal joints of slightly undulate. Gnathopod 2, 5th 

 peraeopods 5-7. h. Gnathopod 1 <J. i. Gnathopod 1 ?. joint in o* with two large teeth on 



inner margin, one near base, the 

 other near hinge, the latter obscurely bifid ; in ? the two teeth are only feebly developed, 

 the basal one more prominent than the distal one. 



Peraeopods 5-7, distal anterior corner of 2nd joint produced ventrally to form a 

 pointed tubercle, more prominent in ? than in J, 3rd moderately expanded, not as wide 

 as 2nd or 4th joints, postero-inferior angle of 4th acute. 



Branchiae very long, nearly (?) or quite (cJ) as long as peraeon segments 2-7 together, 

 single on both segments 3 and 4, accessory appendages in S double on both segments, 

 in length about equal to head (excluding 1st segment) ; in ? only a single short sub-bifid 

 lobe; in juveniles (4-5 mm.) the branchiae are relatively much stouter. 



Length: 3 up to 15 mm., $ up to 10 mm. 



