20,2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



Geographic distribution. — On the slope of the ridge between Wapta 

 Peak and Mount Field, north of Burgess Pass, and about 3800 feet 

 above Field on the line of the Canadian Pacific Railway, British 

 Columbia, Canada. 



Observations. — The generic name is derived from the name Habel 

 as applied to a mountain peak near Wapta glacier at the head of 

 Yoho Valley, British Columbia, Canada. 



HABELIA OPTATA, new species 



Plate 29, fig. 6 



In form the body of this species resembles Yohoia tenuis, but its 

 long slender telson and thoracic appendages quickly separate it. 



The test of the head is finely punctate, and crenulated with minute 

 short spines on the margin. There are eleven body segments bear- 

 ing appendages that are of nearly uniform size, one smaller abdom- 

 inal segment without appendages, and the slender telson. 



The eye has not been observed in any of the four specimens pre- 

 serving the head. 



Appendages. — On one specimen six slender jointed appendages 

 project forward from beneath the carapace ; the posterior of these 

 is a little larger than the others. They represent, in front at least, 

 the first five pairs of appendages of the head. Another specimen 

 shows two slender jointed antennules and posterior to (below) them 

 two larger jointed antennae with delicate spines extending forward ; 

 another antenna is indicated by a small jointed leg-like appendage. 

 The thoracic appendages are somewhat difficult to interpret. One 

 specimen shows the broad terminal joint on eight legs, with traces 

 of it on the three anterior legs ; another specimen has five long, 

 slender, jointed legs with a sixth posterior to them that is not over 

 one-half as long ; back of the latter there are five of the short legs 

 with the broad terminal joint. The five anterior legs have a rather 

 large gill attached to a short exopodite ( ?). 



The terminal joints of the posterior legs have almost the outline 

 of the pleuron of the segments of the thorax ; they gently curve from 

 a broad base to a fine point and have five or more short sharp spines 

 on the anterior margin and somewhat finer spines on the posterior 

 margin ; their function was probably natatory. 



Surface. — The surface of the head test and tergite of the segments 

 is finely punctate. The telson appears to have been longitudinally 

 striate or smooth. 



Dimensions. — The largest specimen has a length of 22 mm. ex- 

 clusive of the long telson, which is about as long as the body. 



Observations. — The presence of this species in the collection was 



