206 POST-TERTIARY ENTOMOSTRACA. 



species, characterised by the tapering and acutely pointed posterior extremity, and by the 

 absence of lateral alar projections, and of any surface-ornament except the very slightest 

 punctation. More extended researches have, however, supplied us with numerous 

 specimens in stages intermediate between this and the fully developed C. Montrosiense, 

 showing the extremity becoming gradually more obtuse and upturned, the shell-surface 

 putting on its characteristic sculpture, and the lateral processes in progress of 

 development. 



Distribution. Recent. — Baffin's Bay. 



Fossil. — Scotland : Tangyburn, Govan, Barrie, Elie, Dryleys, Errol, Annochie, King 

 Edward's. England : Hopton Cliff. Ireland : Woodburn. Norway. 



6, Cytheropteron rectum, Brady. Plate XIV, figs. 17, 18. 



1868. Cytheropteron y.^ctvu, Brady. Monog. Rec. Brit. Ostrac, p. 4/6. 



1869. — — Brady and Robertson. Ann. Mag. N. H., ser. iv, 



vol. iii, p. 372, pi. xx, 

 figs. 6—8. 



Carapace, seen laterally, oblong, quadrangular, very slightly higher in front than 

 behind ; height not equal to half the length ; anterior extremity well rounded ; posterior 

 rounded oS" below, but only slightly above the middle ; superior margin straight, ter- 

 minated at each extremity by a distinct angular elevation, inferior slightly sinuated in 

 front of the middle ; seen from above, ovate, widest behind the middle, where the lateral 

 alae project slightly, forming an obtuse angle, rounded behind, acuminate in front ; width 

 equal to nearly half the length. Surface of the shell closely and minutely punctate, 

 lateral alae almost obsolete. 



Length, -^i\\ of an inch. 



Our single fossil specimen of this species was unfortunately lost when only one figure 

 of it had been drawn. The lateral view given in our plate was, therefore, taken from a 

 recent carapace. 



Distribution. Recent. — Shetland and West of Ireland. 



Fossil. — Scotland : Crofthead. 



7. Cytheropteron angulatum, B. and B. Plate VIII, figs. 37—40. 



1872. Cytheropteron angulatum, Brady and Robertson. Ann. Mag. N. H., 



ser. iv, vol. vi, 

 p. 62, pi. ii, figs. 

 7,8. 



