THE OSTEACODA. 



235 



Stage V. 



Female. — Shell with nearly straight posterior border and deeply convex ventral 

 border. Cephalic organs as in Stage II. female, except that there was only one 

 central bristle on antenna ii. 



CoNCHCECiA HADDONi, Brady & Norman. 

 (Plates 18, 19. figs. 73-89.) 



Miiller expresses the oiiinion (p. 90) that a larger southern race ( ? 2-6 — 2'95, 

 d 2-2 — 2'5)* can be distingaislied from a smaller northern race ( 2 only up to 2-6, d to 1-9), 

 but he recognises tliat this idea is opposed to the fact that Brady's specimens from 

 53° N. (coast of Ireland) belonged to the larger race. He regards a re-investigation of 

 the specimens as urgently needed for the certain identification of the species. My 

 specimens of Stage I. are also large (up to 3 mm.), and leave absolutely no doul)t of 

 their identity with the species of Mtiller and of Brady and Norman ; it is enough to say 

 that they agree point for point, and it is unnecessary to re-describe and re-figure every 

 detail. The collection is short of males, but the extreme sizes which lie gives for females 

 (2-2-2-95) are well within the limits of size-variation of the older stages of a large 

 adult. 



Stage I. 



Female (Mean, 272). — Shell with the posterior border slightly concave above, 

 convex below ; no recognisable postero- ventral angle ; the opening of the right asym- 

 metrical gland is on the posterior border at about one-third of the height; it is not 

 prominent at any stage of either sex ; the shell is highest behind the centre of the 

 length. In Dr. Miiller's figure (xviii. 1) the shell is apparently much higher posteriorly 

 than in my figure 78, but the rostrum shows that the specimen had fallen slightly 

 forward ; my specimens present a similar outline when in the same position. Frontal 

 organ and Antenna i. as figured by Miiller (xviii. 3, 4, 8). Antenna ii.: the Ion"* 

 basal binstle may carry a few short hairs; there is also a small bunch of hairs, difficult 

 to find, on the joint just proximal of this bristle. 



Male (21 mm.). — Shell with the posterior border slightly concave above, but the 

 convex curve protrudes less behind a perpendicular from the postero-dorsal angle than 

 iu the female ; the ventral boi-der is convex ; the highest point at about the middle of 

 the length. Frontal organ and Antenna i. as drawn by Miiller (xviii. G, 7). 

 Antenna ii. with one unusually long basal bristle, and one very short; of the central 

 bristles, the one is about two-thirds of tbe length of the other, both are long and witli 

 fine short hairs. Some of the terminal bristles and tubes witli hairs, as in the 

 female. 



Stage II. 



Female (Mean, 1-GG). — Shell with the posterior border as in Stage I. ; the ventral 

 border convex, so that the greatest height is now about tiie middle of the length. 



* His figure of a female moasiiros 2"8 without the rostrum. 

 SECOND SERIES. — ZOOLOGY, VOL. X. 



40 



