MUSEUM OF COMPARATIVE ZOOLOGY. 67 



Miersia Agassizii, sp. nov. 



Plate XI. Figs. 5-7. Plate XII. Figs. 1-4. 



Male. — The carapax is nearly as broad as high, but is a little compressed above 

 so as to make the dorsum somewhat obtusely angular, though rounded and not 

 at all carinate even anteriorly. The rostrum is imperfect in all the specimens 

 seen, but in the most perfect specimen it was evidently much longer than the 

 carapax proper ; it is very slender, slightly upturned toward the tip, and back 

 of the tip of the antennal scale is armed with seven teeth above and four 

 beneath. The anterior margin projects in an acute, but scarcely spiniform, 

 angle above the base of the antenna, and opposite the base in an acute and 

 laterally prominent branchiostegial spine, below which the branchiostergite is 

 rather suddenly incurved in the anterior part of the carapax. The surface of 

 the carapax and abdomen is naked and smooth to the unaided eye, but is micro- 

 scopically punctate. 



The eyestalks are very short, and terminated by small hemispherical black 

 eyes. The peduncle of the antennula is short, much less than half as long as 

 the antennal scale : the first segment is fully as long as the second and third 

 taken together, is deeply excavated above for the reception of the eye, and its 

 outer edge is armed distally with a small tooth ; the second and third seg- 

 ments are broader than long and subc3dindrical. The outer or major flagel- 

 lum is nearly twice as long as the antennal scale, with the proximal portion 

 for about half the length of the antennal scale compressed vertically, broadly 

 expanded, and thickly clothed beneath with fine hairs, but the distal portion is 

 very slender and somewhat compressed vertically. The antennal scale is about 

 three fourths as long as the carapax excluding the rostrum, and near the base 

 about a fourth as broad as long, but narrowed regularly to a very slender tip. 

 The second segment of the peduncle is armed with an acute dentiform spine 

 below, and a triangular tooth above the base of the scale. The distal segment 

 of the peduncle reaches only about a third of the way from the base to the 

 tip of the antennal scale. The flagellum is wanting in all the specimens 

 examined. 



The labrum is fleshy, prominent as seen in front, and the inferior edge is 

 thickened and slightly indurated and applied to the concave dorsal surfaces of 

 the mandibles. The lobes of the metastome are very broad distally and some- 

 what truncated. The mandibles (PI. XII. figs. 1, l a ) are expanded into thin, 

 dorsally concave and strongly dentate ventral, processes, above and closely 

 connected with which are small and narrow molar areas. The opposing edges 

 of the ventral processes differ somewhat on the two sides : on the right side, as 

 shown in the figures, the mesial edge is slightly convex as seen from above or 

 below, and armed with about eight acutely triangular teeth, beyond which there 

 are several small teeth on the anterior edge ; on the left side the mesial edge as 

 seen from above or below is straight or slightly concave, terminates anteriorly 

 in a sharp angle beyond which there are no teeth on the anterior edge, and the 



