256 t)K. G. H. FOWLER— BlSCAYAJSr PLANKTOK : 



sense-tubes subcqual iu lengtli, and one long bristle -which caiTics few minute hairs. 

 Antenna ii. The right and left hooks arc nearly synanictrical and subcqual: the 

 right is rather the stouter of the two ; it begins by a short straight piece, and after an 

 angle forms a sickle-shaped curve. The two central bristles (much foreshortened in 

 fig. 267) are subcqual, the one carrying short fine hairs. There are two basal bristles, 

 the one nearly twice the length of the other. 



The single specimen was in fair condition, fortunately, as the cephalic organs were 

 hitherto undescribed. 



Female (Mean, 2'51). — Shell Avith the height about 73 percent.* of the length. The 

 tw^o shells together form almost a sphere when viewed from a longitudinal vertical 

 plane. The postero-dorsal angle is rounded, the posterior border slightly convex, no 

 postero-ventral angle, a strongly convex ventral border. E-ostrum bent sharply 

 downwards, its apex at about two-thirds of the height of the shell ; it projects very 

 little beyond the anterior border. Erontal organ as described and figured by Miiller 

 (viii. 19), with the addition usually of a thickened groove (? joint) near the base of the 

 terminal segment. Antenna i. as described bv Miiller. Antenna ii. wdth two 

 central bristles, the one about tAvo-thirds of the length of the otlier, both hairless ; there 

 is sometimes also a small basal bristle. 



Stage II. 



Eemale (Mean, l'5-l). — Shell with the height about 8 i< per cent, of the length; it 

 agrees with Stage I. except in being proportionately higher. Cephalic organs as 

 in Stage I. 



Stage III. 



Eemale (Mean, 0-95). — Shell nearly as high as long, very sharply curved vcntrally. 

 Cephalic organs as in later stages. 



Stage IV. 



Female (Mean, 0"61). — Shell as in Stage III. Frontal organ and antenna i. as in 

 later stages. Antenna ii, with one long central bristle. 



Stage V. 



Female (0-1 mm.). — Shell as in Stage IV. The frontal organ and antenna i. wore 

 unfortunately broken in dissecting the single specimen. Antenna ii. us in Stage IV. 



Archiconch(ECIA cucullata, Brady. 



Two males and tAvo females of this rare species were captured. The females Avere 

 apparently at Stage II. or III., but offered no structural differences from Miillcr's 

 description and figures which require comment here. 



* The specimen figured Ly Dr. Miiller (viii. 13) Bi)pears lo have Ijeeu tilted a little veulrally. 



