168 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 41 



short bristles or cilia; from anterior view labrum with anterior lobe 

 broadly triangular, keeled dorsally, and posterior lobe narrower, sides 

 sinuate but approximately parallel, the tip trilobed, the middle lobe 

 bearing the bristles or cilia. Mandible not distinctive. Maxilla 

 with two teeth, densely bristled; the basal arm broad, its distal 

 boundary and outer tooth forming a continuous semicircular curve. 



Legs or thoracic appendages five, conforming strictly to generic type. 



Postabdomen broad, length medium; dorsal margin concave be- 

 yond anal angle, and broadly rounded at end; proximal half ciliated, 

 distal half with double row of twelve teeth in each row, quite strong 

 for this genus, diminishing slightly distally. Laterally a row of cilia 

 from base of caudal claw to a point near anal angle. Terminal claw 

 strong, slightly curved and crumpled; concave border ciliated to tip; 

 basal spines two, the distal twice the size of the proximal. 



Measurements. 



Length of body 



Length over all 



Width of body 



Width over all 



Height of body 



Height over all 



Length of horn 



Highest ridge 



Diameter of largest hexagonal cell 



Diameter of average hexagonal cell 



Depth of average cell 



Length of terminal claw 



Length of postabdomen from anal setae to claw. 



mm. 



0.620 

 .760 

 .480 

 .720 

 .560 

 .730 

 .140 

 .120 

 .075 

 .050 

 .040 

 .075 

 .245 



The variations in proportions are at once apparent; the greatest 

 extremes are in the length of the horn. An analysis of these pro- 

 portions expressed in percentages of the length shows no significant 

 correlation. On the whole, there are more minimum proportions 

 among the smallest specimens and more of the maximum proportions 

 among the larger specimens. But the totals of the proportion per- 

 centages are larger for the smaller individuals and smaller for the larger 

 individuals, with an exception in each group. The 0.60 mm. speci- 

 men is the only one not extreme in any of the structures measured; 

 each of the others is extreme, maximum or minimum, in from three 

 to six proportions measured. The variation is dependent upon locality 

 rather than upon age or size. Specimens from one collecting station 

 (mouth of Northwest River) furnished the long-horned specimens; 

 another locality (mouth of Sucker Brook) the short-horned individuals. 

 Specimens from other localities seem to be more average in this par- 

 ticular* Specimens from New Jersey are of the short-horned type. 



Eggs, two. 



Male. — Unknown. 



Color, yellowish. 



