242 DR. G. H. FOWLER— BISCATAN PLANKTON : 



Antenna ii. witli slender central bristles, the one nearly twice the length of the other ; 

 hairs, if present, extremely minnte. No basal bristles. 



Ill both sexes and notably in the female the lateral glands are often difficult to see : 

 the gland of the left shell is often more easily detected with a low power than its opening 

 with a high power. In many specimens the anterior ventral part of the shell is extra- 

 ordinarily glandular. 



Stage II. {loricata stage). 



Male (Mean, 1-75). — Shell much as in Stage I. ; intermediate between that figured 

 by Miiller (xxii. 12) for loricata, var. minor, and that which he gives for loricata, var. 

 typica (xxii. 1), in that the posterior border is more nearly perpendicular to the dorsal 

 border than in the typical form ; but the ventral border is more taj)ered, with the highest 

 point behind the middle of the shell, as in the smaller variety. The lateral glands ar6 

 in the usual position for the species. Frontal organ as figured by Miiller (xxii. 4). 

 Antenna i. with about 22 pairs of teeth, the paired arrangement is practically carried 

 out to the proximal end of the rows, unlike the markedly alternating condition noticeable 

 in magna at this stage. The distal accessory bristle carried about 13 fine teeth ; the 

 proximal had also a few, which were difficult to see. Antenna ii. as drawn by Miiller 

 (xxii. 6, 7), except that the hairs on the longer central bristle were not quite so long in 

 ray .specimens. 



Female (Mean, 2'0). — Shell much as in Stage I. ; the lateral glands present, but 

 difficult to see ; the posterior border not so prominent as in Stage I. Cephalic organs 

 as described and figured by Miiller (xxii. 3), except that fine hairs occurred on more than 

 one terminal bristle. 



Stage III. 



Male (1'4). — Shell more tapered antero-ventrally than in later stages, and therefore 

 more resembliDg their female type ; the lateral glands clearly visible. Frontal organ 

 long, unsegmented ; the terminal part slightly thicker than the stem, the end bent 

 strongly downwards to a blunt spike. Antenna i. with principal bristle of female 

 character. Antenna ii. with one basal and two central bristles, all liairless. 



Female (Mean, 1-3). — Shell very much as in Stage II.; lateral gland visible. 

 Frontal organ unsegmented; the terminal part thicker than the stem ; its blunt spike 

 not so much bent downwards as in the male at this stage. Antenna i. without a dorsal 

 bristle. Antenna ii. as in the male of this stage, but without a basal bristle. 



CONCH(ECIA MAGNA, ClauS. 

 = 7nacrocheira, Miiller. 



(Plates 21, 22. figs. 139-160.) 



This was the most plentiful of the larger forms in the collection, and was apparently 



represented by five stages. But it was hard to settle under what name it should go, 



owing to the difficulty of deciding whether the penultimate stage belonged to subarcuata, 



Clans, or to marjna, Claus ; thes(5 two names are of tlie sann^ date. The original source 



