OF THE ANTWERP CRAG. 395 
CYTHERE MucRoNATA, Sars. (Plate LX VII. figs. 3 a—3 d.) 
Cythere mucronata, G. O. Sars, Oversigt af Norges Marine Ostrae. p. 48. 
Cythere spinosissima, Brady, Trans. Zool. Soc. (1865), vol. v. p. 386, pl. lx. figs. 10 a-e. 
Carapace, as seen from the side, subquadrangular, of nearly equal height throughout, 
height equal to fully half the length; extremities rounded; superior and inferior 
margins nearly parallel; the entire circumference (except the upper half of the anterior 
margin) beset with blunt squamous spines, which are often dilated at the free extre- 
mity, those of the postero-inferior angle being very long. Seen from above, the outline 
is rhomboidal, much broken up with spinous projections. ‘The sides of the valves are 
beset with flattened squamous spines, often so much dilated at the end as to become 
quite fan-shaped. End view hatchet-shaped. Length 3/5 inch (1°3 millim.). 
The spinous armature of this fine species is subject to great variation in the extent 
of its development, the figures given in Pl. LXVII. exhibiting the most extreme form 
with which I am acquainted ; it is found in the living state off the coasts of Norway. 
The fossil specimens occurred in the ‘Sables moyens,” zone a Bryozoaires. 
CYTHERE JONESI (Baird). (Plate LX VII. figs. 2 a—2 d.) 
Cythereis jonesii, Baird, Brit. Entom. p. 175, pl. xx. fig. 1 (1850) ; Norman, Nat.-Hist. Trans. 
Northumberland and Durham, vol. i. p. 21, pl. vil. figs. 5-8 (1865). 
Cythere ceratoptera, Bosquet, Entom. foss. terr. Tert. France, &c. (1852), p. 114, pl. vi. fig. 2. 
Cythereis ceratoptera, Jones, Monog. Tert. Entom. Eng. p. 39, pl. iv. fig. 1 (1856). 
? Cythereis cornuta, Jones, Entom. Tert. Form. Eng. p. 39, pl. iv. fig. 19. 
Cythereis fimbriata, Norman, Ann. & Mag. Nat. Hist. ser. 3, vol. ix. pl. i. fig. 9 (1862). 
Cythereis spectabilis, Sars, Oversigt af Norges marine Ostrac. p. 46. 
Cythere jonesii, Brady, Monog. Recent Brit. Ostrac. p. 418, pl. xxx. figs. 13-16 (1865); Brady, 
Crosskey, and Robertson, Monog. Post-tert. Entom. Scotland, &c., p. 171, pl. xii. figs. 4-7. 
Carapace, as seen from the side, oblong subovate, higher in front than behind ; height 
equal to more than half the length; anterior extremity rounded, fringed with blunt 
spines ; posterior also rounded, bearing a smaller number (about 5) of longer spines ; 
dorsal and ventral margins nearly parallel and much broken up into irregular spines ; 
over the anterior hinge is one very large and strong spine. Outline, as seen from above, 
rhomboidal, greatest width behind the middle and equal to about two thirds of the 
length. End view triangular. The surface of the valves, except along the margins, is 
smooth and gently undulated ; there is a distinct elevated and rounded ridge just within 
the anterior and posterior extremities ; and the general surface of the valves suddenly sinks 
to a lower plane at a little distance behind the middle. Length 35 inch (1-1 millim.). 
I was at one time disposed to think that the form described by M. Bosquet as C. cera- 
toptera might well be kept apart as a distinct variety of C. jonesti; but, after exami- 
nation of a large number of recent and fossil specimens, I now believe that there is no 
character sufficiently persistent to warrant even this separation, the chief variations 
VOL. X.—ParT vill. No. 8.—August 1st, 1878. 3H 
