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



central bristles, the one about two-thirds of the other, each with a very few fine short 

 hairs. One at least of the terminal bristles may carry a row of short spines. 



Male (Mean, I'SO). — Shell not markedly different from that of the female. In the 

 specimen drawn in figure 225 a blunt j)i'ocess replaced the spines; this may have 

 been due to damage ; the spines are generally conspicuous. Tlie characteristic cephalic 

 organs as drawn by Mviller (pi. ix.). 



Stage lit. 



Female (Mean, 1'41). — Shell of the same character as in Stage II., but the rostrum 

 somewhat less markedly bent downwards. The antero-ventral gland-cells persist. Erontal 

 organ spineless, unsegmented ; of the same general character as in Stage II., tliat is, 

 a swollen convex ventral border is suddenly decreased anteriorly to form with the dorsal 

 border an acute tip. Antenna i. usually (? always) without a dorsal bristle. Antenna ii. 

 as in Stage II., but the central bristles are apparently hairless. 



Male (Mean, l-^l). — Shell as in Stage II. Frontal organ approaching the female 

 type of Stages II. and III., but shorter, and with the dorsal border rising suddenly about 

 the middle of the future terminal joint ; spineless, unsegmented. Antenna i. with the 

 principal bristle of female type. Antenna ii. as in female of Stage II. 



Stage IV. 



Female (Mean, 0-98). — Shell much as in the later stages, but the posterior border is 

 rather straighter, and is not shaved off so much at the postero-ventral angle. One or 

 two of the large antero-ventral gland-cells are generally recognisable. The spines of 

 the right shell are sometimes present. Frontal organ ending bluntly, the ventral 

 border decreasing suddenly near the tip as before : the organ is shorter in proportion to 

 the antennae. An'tenna ii. with the longer central bristle about twice the length of 

 the shorter. 



Male (Mean, I'OS). — Practically indistinguishable from the female, except for the 

 rudiments of the penis. 



Conchcecia spinirostris, Glaus. 



= C. purrecta, Clans. 



(Plates 24, 25. figs. 23G-246.) 



The relation of the different stages is discussed in the Developmental Part (p. 276). 



Stage I. {porrecta stage). 



Male (1-3 mm.). Shell of the type of magna male: the slioulder - ridge well 

 developed ; the opening of the right asymmetrical gland rather prominent posteriorly. 

 The posterior border nearly at right angles to the dorsal border, with a slight re-entrant 

 curve; ventral border nearly straight. Frontal organ much thicker than the stem ; 

 constricted centrally, thickest distally ; spines very few and short. Antenna i. : the 

 armature of the principal bristle appeared to consist of about IG pairs of saw-like teeth, 

 followed by about 11 pairs of spine-teeth; the latter so markedly alternate as to suggest 



