250 College of Forestry 



head, the swollen mesothorax, and the laterally expanded gill- 

 bearing portion of the abdomen. 



General coloration pale, head with a pair of oblique zigzag 

 bands extending backward from the eyes to the middle of the 

 occiput, prothorax wholly pale above. Mesothorax some- 

 what darker across front and rear ends, and with a pair of 

 curved black pencilings upon the middle of the dorsum. Abdo- 

 men with basal black mid-dorsal triangles on the segments 

 in front and at rear ; the gill-bearing middle segments obscurely 

 brownish. There is also a pale brownish transverse line on 

 either side of each segment near the lateral margin toward 

 the front, and there is a pair of black dashes upon the rear 

 of segment 10 above. Caudal filaments wholly pale, but in 

 the darkest of the specimens showing very faint rings. Legs 

 slender, increasing in length posteriorly, pale in color with a 

 single brown submedium band on each segment. Claws gently 

 curved, very long and slender and attenuate to a very sharp 

 point, about equal in length to one-half of the tarsus. 



Gills on segments i to 6. On segment i, a long, erect taper- 

 ing, lash-like rudiment set obliquely upon a short pedicel. 

 On 2, a pair of quadrate opercua, straight margined on the 

 front and within, more rounded externally and at the rear, 

 bearing an oblique ridge that runs from the basal external 

 articulation inward; brownish in color, with paler margins 

 and with a pale Y-spot upon the middle, opening forward, 

 one arm of the Y lying upon the dorsal ridge. Gills on seg- 

 ments 3, 4, 5 and 6 thin and lamelliform with a wide border 

 of forking filaments wider than the body of the gill, all these 

 filaments forking unilaterally, the branches springing from the 

 inner side of the filament and all lying in one plane. These 

 true gills diminish in size posteriorly, that of the sixth segment 

 being about half as large as that of the third. 



The gill-bearing segments are broadly depressed and later- 

 ally expanded into huge lateral spines, which, from above, 

 have the aspect of a segment of a circular saw. The lateral 

 tooth on segment 2 is obtusely pointed, all the others very 

 sharply pointed, highest on fourth and fifth and directed more 

 strongly toward the rear of each succeeding segment. Seg- 



