334 PROCEEDINGS OP THE ACADEMY OP 



CERATIOCARIS (COLPOCARIS) ELYTROIDES, Meek. 

 Carapace-valves narrow-subelliptic, about two and a half to 

 three times as long as high, anterior end narrower than the other, 

 and subangular above ; dorsal margin gently arcuate from end to 

 end, and terminating behind in a pointed projection that extends a 

 little farther backward than the lower margin, and curves distinctly 

 downward ; posterior margin truncated obliquely from above for- 

 ward and downward, and very deeply sinuous, the sinus being 

 directed a little upward and forward ; basal margin most promi- 

 nent near the middle, and behind this straight, or sometimes very 

 faintly sinuous and ascending to the rather obtusely pointed pos- 

 terior basal extremity, while from near the middle forward it 

 ascends gradually, at first with slight convexity of outline, and 

 farther forward with a stronger upward curve, until it intersects 

 the dorsal margin above, at a more or less obtuse angle. Surface 

 writh an obscure linear, sometimes minutely crenate carina, or 

 raised line along near the lower margin, but not exactly parallel 

 to it (being most remote from it along near the middle), and an- 

 other similar but more distinctly crenate carina, running along 

 parallel to, and about one-fifth the height of tlie valves below, 

 the dorsal margin ; otherwise appearing to the unassisted eye as 

 if perfectly smooth, but, when examined in a favorable light, by 

 the aid of the highest power that can be conveniently used as a 

 hand magnifier, seen to be very beautifully and minutely striated, 

 the strise being very regular, closely arranged, and more or less 

 divaricating from the caringe. 



Length of carapace-valves, 1.25 inches; height, 0.46 inch; con- 

 vexity of each valve, 0.09 inch. 



This species may be readily distinguished from the last, not 

 only by its smaller size, but by its narrower form, and its two 

 minutely crenate longitudinal carinse, and particularly by the dif- 

 ferent nature of its microscopical sculpturing, that of the last- 

 described species presenting a delicate reticulated appearance, 

 instead of minute hair-lines. The basal margins of its valves, 

 below the carina, are also only a little deflected inward and down- 

 ward, while in all the specimens of the latter, yet seen, they are 

 abruptly deflected at an acute angle inward and upward. 

 Locality and position. — Same as last. 



[March 19, 



