78 PROCh'EDIWGS OF THE NATIONAJ. MUSEUM. vol.53. 



of forked horns, one pair lateral and one ventral, and a pair of unira- 

 mose swimming legs between the bases of the ventral horns. Trunk 

 triangular, the dorsal margin nearly straight, the ventral margin 

 strongly convex, these two forming the sides of the triangle; pos- 

 terior margin or base of the triangle also nearly stright. Neck 

 attached a short distance behind the anterior end or apex of the 

 triangle, on the dorsal surface and not on the median line. Neck 

 also twisted at right angles to the trunk, as in the other species, so 

 that the ventral surface faces the lateral surface of the trunk. Egg 

 strings attached on a level with the dorsal surface and standing out 

 on either side so that they almost form a straight line at right angles 

 to the trunk axis. Each string is comparatively long and thick, and 

 the coils of the spiral are separated a little from one another. 



Color (preserved material), neck and trunk a brownish yellow, 

 egg strings orange j^ellow. 



Length of trunk, 3 mm. ; greatest diameter, 2 mm. Length of egg 

 coils, 3.50 mm. ; diameter, 1 mm. Diameter of egg strings, 0.33 mm. 



{diversus, divergent, alluding to the egg coils.) 



Remarks. — Since there is but a single mutilated specimen, it seems 

 at first sight presumptuous to establish a new species for it. But it 

 presents so many striking differences as to leave no doubt of its being 

 a new species, and supplements the characters of the genus in such 

 a way as to demand recognition. In cincinnatus the fourth thorax 

 segment carried two pairs of profusely branched horns, with the 

 fourth legs entirely concealed between their bases so that they 

 escaped notice. In triangulus there were but three horns in the 

 form of simple spines, and the unpaired ventral horn stood between 

 the widely separated fourth legs. Here in diversus there are again 

 two pairs of horns, but the ventral pair are only forked once, and 

 the fourth legs are close together between their bases and are only 

 partially concealed. 



Again, in cincinnatus and triangulus the neck is attached to the 

 extreme anterior corner of the trunk; here it is removed a short 

 distance from the anterior end on the dorsal surface and is still 

 attached to one side of the midline. Finally the egg strings which 

 are parallel in all the other genera and species in which they are 

 coiled are here so widely separated as almost to form one straight 

 line at right angles to the axis of the trunk. 



COLLIPRAVUS, new genus. 



External generic characters of female. — Cephalothorax oblong, 

 nearly cylindrical, sending out laterally two pairs and ventrally one 

 pair of cushion-like processes. Second, third, and fourth thorax seg- 

 ments distinctly separated, each with a pair of cushion-like lateral 

 processes. Neck narrow and chitinized, bent just behind the fourth 



