60 RATHBUN 
H. Maxilliped with exopod :). .. . « pusiola, 
H’. Maxilliped without exopod. 
J. Antennal scale about same length as, or shorter 
than, telson .. . « brevirostris. 
J’. Antennal scale longer than telson . . palpator. 
F’. Rostrum reaching second segment of antennular pe- 
duncle. 
G. Rostrum straight . . . ee «| Meramani: 
G’. Rostrum arched over the eye. 
H. Fourth segment of abdomen with lateral spinule. 
Maxillipeds reaching, or nearly reaching, end of 
acicle : : cristata. 
H’. Fourth segment of abdomen unarmed. Maxillipeds 
reaching only to distal third of acicle .  stoneyi. 
SPECIES OF SPIRONTOCARIS, ARRANGED ACCORDING TO THEIR 
EXOPODS AND EPIPODS. 
A. One or more supraorbital spines present. 
B. Third maxilliped with exopod and epipod. 
C. First thoracic foot with epipod. . . , 2) ee See. 
C’. First and second thoracic feet with epipods : bispinosa, snyderi. 
C’, First, second, and third thoracic feet with epipods 
prionota, lamellicornis, spina, arcuata, murdocht, 
truncata?, liljeborgit, phippsit, ochotensis, dal. 
B’. Third maxilliped without exopod but with epipod. 
C. First thoracic foot with epipod . . = » icing: 
C’. First and second thoracic feet with epipods polaris, unalaskensis. 
C”. First, second, and third thoracic feet with epipods 
greniandica, washingtoniana. 
B’. Exopods'and epipods unknown 9. 4s. <<. « « «Gents. 
A’. No supraorbital spine or spines. 
B. Third maxilliped with exopod and epipod. 
C. Thoracic feet without epipods darbata, biunguis, macrophthalma. 
C’. First thoracic foot with epipod 
Jabricii (usually), suckleyt (usually). 
C”. First and second thoracic feet with epipods 
Jabricii (sometimes), gaimardi bel- 
chert, townsendi, suckleyi (sometimes). 
C’’. First, second, and third thoracic feet with epipods 
pusiola, herdmani, stoneyi, avina, macilenta. 
B’. Third maxilliped without exopod but with epipod. 
C. Thoracic feet without epipods 
decora, tridens, stylus, maxilhipes, 
brachydactyla, camtschatica, Rincaidi. 
C’. First thoracic foot with epipod . . . . moseri, sitchensis. 
C”. First and second thoracic feet with epipods 
fiexa, picta, paludicola. 
C’, First, second, and third thoracic feet with epipods 
carinata, palpator, brevirostris, taylori, cristata. 
