236 DE. G. H. FOWLEE—BISCATAN PLANKTON : 



Frontal organ unsegmented, spineless, swollen anteriorly. Antenna ii. retaining 

 the loiig basal bristle ; the hairs on the terminal bristles and tubes few or alisent. 

 Male (Mean, ? +1--15). — This stage was not observed. 



Stage III. 



Female (Mean, 1-01). — Shell with the posterior border not projecting so far pos- 

 teriorly as in the later stages ; the ventral border is more sharply convex ; the height 

 more than half the length. Frontal organ fairly long, blunt, spineless, somewhat 

 swollen anteriorly. Antenna ii. with a short basal bristle, difficult to see in most 

 positions. No hairs on the terminal bristles or tubes. 



Male (1-0 mm.). — Shell with the posterior border as in Stage I., but the height rather 

 greater in proportion to the length. Frontal organ as in the female of this .stage, 

 but rather shorter. Antenna i. with the principal bristle of female character. 

 Antenna ii. much as in the female. No hairs on any of the bristles. 



Stage IV. 



Female (Mean, 0-66). — Shell more sharply convex ventrally than in Stage III. 

 Antenna ii. with no basal bristles and only one long central bristle. 

 Male. — This stage was not observed. 



In Stages III. and IV. the lai"ge gland-cells described and figured by Miiller (xviii. 2) 

 were sometimes very conspicuous. 



Stage V. 



Female (of 0"4! mm.). — The high position of the opening of the right asymmetrical 

 gland seems to indicate that this was attributable to haddoni. Shell with the height 

 about five-sevenths of the lengtli, very sharply convex ventrally. Frontal organ much 

 as in Stage IV. Antenna ii. as in Stage IV. 



Male of this stacje not observed. 



CoNCHCECiA hyalophyllum, Claus. 

 = C. lophiira, Miiller. 

 (Plates 19, 20. figs. 90-109.) 

 Stage I. {lojihura stage). 



Female (Mean, ±23). — Shell with the posterior border forming a flattened curve ; 

 no marked postero-ventral angle; the ventral border slightly arcuate, and the shell 

 higher behind the arena tion than in front. Lateral glands well-marked ; a collection of 

 long cells on the ventral border of the left shell behind the arcuation was less pronounced 

 than in Miiller's figure of lophara (xx. 2), biit clearly recognisable. Frontal organ 

 incompletely segmented ; the terminal joint gradually enlarging distally, then abruptly 

 constricted ventrally to form a sharp, downwardly directed spine. There are numerous 

 fine spines on the dorsal border, and stout spines on the ventral border ; the Avhole 

 structure closely resembling that figured by Midler for lophura (xx. 10). Antenna i. 

 Avitli a long dorsal bristle carrying fine hairs. Antenna ii. with two central bristles; 



