412 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxm. 



The oviducts are coiled once in the genital segment, the three 

 strands of the coil running the entire length of the segment. The 

 semen receptacles are very similar to those of JicoZor, horseshoe-shaped, 

 with the ends somewhat enlarged. 



The cement glands can not be seen in mature females on account of 

 the pigment on the dorsal surface of the segment and in the eggs that 

 fill the coiled oviduct, but they can be distinguished in young females. 

 They are narrow and rod-like, close to the intestine on either side, 

 and more or less sinuate; the component cells are very short and 

 flattened like the eggs in the egg-strings. 



Total length, 9 mm. ; length of carapace on mid-line, 3.5 mm. ; width 

 across posterior margin, 4.5 mm. ; length of first dorsal plates, 2 mm. ; 

 of second plates, 0.85 mm.; of third plates, 2 mm.; of sixth segment 

 plate, 1.5 mm.; of egg-strings, 15 mm. 



Color a rich brownish black, the margins of the carapace and of the 

 dorsal plates, and a semicircular spot through the eyes much lighter 

 and yellowish or reddish. The anal laminae are also without pigment. 



{smithii. Named for Prof. S. I. Smith, of Yale University.) 



Young females. — In a young female only 3 mm. long the carapace is 

 strongly wedge-shaped, the posterior margin twice the width at the 

 frontal plates, the teeth along its central portion comparatively larger 

 and blunter than in the adult. The lateral margins are nearly straight 

 atid show a well-defined notch, armed with two minute teeth, about 

 three-fifths of the distance from the frontal plates. This notch evi- 

 dently indicates the point of junction of the cephalic and thoracic 

 portions of the carapace. The eyes are also plainly visible close to the 

 mid-line, in the anterior third of the carapace. 



The dorsal plates of the thorax are in a rudimentary condition ; the 

 first two pairs are about the same size and the third pair a trifle larger; 

 the first pair does not quite touch the anterior margin of the tliird 

 pair, and only the extreme tips of the second pair overlap the tliird. 



The genital segment is thus left almost entirely free dorsally; on 

 its ventral surface just in front of the openings of the oviducts may 

 be seen the rudiments of a pair of swimming legs, in the form of two 

 spines on either side, close together, the inner one broadly triangular, 

 the outer one minute and very slender. 



These afterwards disappear, or at least they can not be distinguished 

 in the adult. 



The sixth segment plate is circular and one-third the width of the 

 genital segment; the anal laminae are much longer than this plate, 

 comparatively slender, and the wings are not yet fully formed along 

 their inner margins, which are armed at this stage with three small 

 spines. The ventral plate of the abdomen reaches nearly to the pos- 

 terior margin of the sixth segment plate and is much broader than the 

 latter, more than half the width of the genital segment. The append- 



