244 DE. Gr. H. FOWLER— BISCATAlSr PLANETOJST : 



about as lono- as the principal bristle, with a few minute teeth. Antenna ii. with its 

 inner branch as clrtiwn by Miiller (xxi. 3). The longer central bristle carries numerous 

 lono- fine hairs (? 8-10 pairs) ; both central bristles are curved, especially the shorter. 

 The lono-er basal bristle is about twice the length of the shorter. 



Stage II. (magna stage). 



Female (Mean, 1"88). — Shell much as in the subsequent Stage I., but the rostrum 

 is less markedly bent downwards and the shoulder-ridge slightly more marked. Er ontal 

 organ much as drawn by Miiller (Nap. Monogr. 1894, pi. v. tig. 8), but slightly more 

 swollen anteriorly, though not so much so as in liyalophyllimi. Terminal spike very 

 rarely suppressed. Antenna i. with a long slender dorsal bristle carrying a few 

 extremely minute hairs. Antenna ii. : the longer central bristle carries fewer hairs 

 than in the subsequent Stage I. No basal bristles. 



Male (Mean, 1-77). — Shell much as in subsequent Stage I., but the anterior border 

 rises more sharply, giving a less bluff-bowed outline. Frontal organ much as in sub- 

 sequent stage. Antenna i. without spines on the terminal joint. The armature of the 

 principal bristle formed by 21-23 pairs of teeth, not markedly shorter at the ends than 

 in the middle ; the distal teeth rather closer together ; about the middle of the row 

 (compare Miiller, xxi. 12) the pairs are rather further apart, and the teeth are not set 

 quite evenly opposite one another, yet are not so markedly displaced as in Milller's 

 drawing of suharcuata (xxi. 23) ; they are also more slender and longer than in that 

 figure. Antenna ii. as figured by Miiller (xxi. 17, 18) ; the hairs on the longer central 

 bristle fewer than in the subsequent stage (apparently 2-5 pairs). Longer basal bristle 

 about tmce tbe length of the shorter. 



Stage III. 



Female (Mean, 1'14). — Shell of the same general type as in the later stages, but 

 shorter and higher ; shoulder-ridge hardly developed. Opening of the left asymmetrical 

 gland slightly prominent above the dorsal border when viewed from the right side. The 

 shell is sometimes sli2;htlv higher in front of the arcuation than behind it. Frontal 

 organ unsegmented, acutely pointed, the terminal part very little thicker than the shaft. 

 The pointed tip is usually in, or nearly in, the same liae as the axis of the organ, but is 

 occasionally slightly bent downwards * (fig. 159). There are a iew fine spines on the 

 ventral surface. Antenna i. with a short thickish dorsal bristle, not carrying hairs. 

 Antenna ii. with the longer central bristle generally carrying a few fine hairs, but 

 sometimes it is bald 



Male (Mean, 1-22). — Shell of a more female cliaracter than in subsequent stages ; 

 that is to say, the rostrum is more downwardly directed, and the posterior border more 

 curved. The shell is often slightly higher in front of the arcuation than behind it ; and 

 is practically indistinguishable from the female shell of the same stage. Frontal 

 organ unsegmented ; the terminal portion is slightly broader than the shaft, generally 



* Quei-j', h/ahjo7ii/llum ? but no lateral glauds were detected. 



