NO. 2192. DRAG0NFLIE8, CALIFORNIA AND NEVADA—KENNEDY. 547 

 OPHIOGOMPHUS BISON Selye, nymph. 



A dark, heavily mottled nymph, very hairy, in which character it 

 resembles mornsoni; 27-33 labial teeth, those at either end of the row- 

 being only half as long as the median teeth. Abdomen with the dorsal 

 hooks on segments 2-9 longer than in the other species ^ and heavier; 

 lateral hooks on segments 6-9. The paired superior appendages 

 three-fourths the length of the median appendage. (See figs. 222, 224- 

 226, and 239.) 



Length, 28-29 mm.; abdomen, 17.5; hind femur, 4,5; width of 

 abdomen, 8.5-9. 



The above description is from exuviae collected on the San Lorenzo 

 River near Santa Cruz, which is the type locality for the imago of 

 the species. I have not taken this emerging, but no other species 

 was collected on this stream and these exuviae agree with exuviae 

 I have collected at Chico, where hison was on the wing. Needham's 

 description of nymphs and exuviae collected by Schwarz on Lake 

 Tahoe fits my exuviae of lison, but I found mornsoni on Lake Tahoe 

 and only mornsoni in the Tahoe region. I believe the locality given 

 is a mistake. Mornsoni is. a species of the cool upper limit of gom- 

 phine life occurring at from 4,000 to 10,000 feet elevation, while 

 all my records for hison are from the low hot valleys of central Cali- 

 fornia. 



OPHIOGOMPHUS OCCIDENTIS Hagen, nymph. 



A medium colored nymph; a lengthwise row of small fight spots 

 along either side of the dorsum of the abdomen. Only moderately 

 hirsute, more hairy than the nevadensis exuvia from Winnemucca 

 Slough, but less so than severus; 21-25 labial teeth which are equal 

 in length thi'oughout the row. Abdomen with dorsal hooks on seg- 

 ments 2-9, these noticeably variable in height and strength, but 

 usually with the fii'st hook slender, erect, the remainder short and 

 heavy. Lateral hooks on segments 6-9. The paired superior ap- 

 pendages two-thirds the length of the median appendage. (See figs. 

 223, 236-238, and 240.) 



Length, 28 mm.; abdomen, 18; hind femur, 4.5; width of a1)- 

 domen, 8-8.5. 



The above description is from exuviae collected on the Columbia 

 River at UmatiUa, Oregon. I am sure of the identity of this, though 

 I took none actually emerging. 



OPHIOGOMPHUS OCCIDENTIS CALIFORNICUS Kennedy, nymph. 



I have eight occidentis exuviae from the American River at 

 Sacramento, Cahfornia. These are probably of the yellow variety, 

 californicus, but I can see no characters separating them from the 

 occidentis nymphs of the Columbia River. In these the lateral ab- 



i Not longer than in morrisoni and montanus, but in these they are slender. 



