98 BULLETIN OF THE ESSEX INSTITUTE. 



Caradina pasadence n. sp. Carapax smooth, ecarinate 

 above, rostrum long, three -fourths the length of the cara- 

 pax, and exceeding by a third of its length the antennular 

 peduncle. It is smooth above, its apex minutely bifid, and 

 occasionally a small tooth beneath at about the level of the 

 extremity of the antennular peduncle. Pterygostomian 

 spine present, rather obtuse ; external angle of the orbit 

 spiniform. Antennula with external spiniform scale on 

 the outer margin of the basal joint, reaching slightly in 

 advance of the extremity of the joint, a small spine on the 

 inner margin of the joint. Antennal flagella subequal in 

 length, the length about equal to that of the carapax with- 

 out the rostrum. Antennal scale about four times as 

 long as broad, extending slightly beyond the antennular 

 peduncle ; its external margin straight, its apex obliquely 

 rounded ; antennal flagelluni about two-thirds the length 

 of the ])ody. External maxillipeds pediform, the ischium 

 strongly arcuate ; the terminal joints partly fused and 

 armed with two rows of spines ; exopodite slender, filiform, 

 joints obsolete. First pair of pereiopoda short, rather 

 stout, the meros about equal to the propodus in length ; 

 hand of regular Atyid character, the fingers excavate and 

 furnished with pencils of hairs. Second pair of pereio- 

 poda about twice the length of first, the carpus simple, 

 slightly obconical, and longer than any other joint ; fin- 

 gers excavate and pencilled. Remaining pereiopoda elon- 

 gate, pediform, with moderate, slightly curved dactyli, 

 spinulose beneath. Telson with straight, converging sides, 

 its apex truncate and spinulose. Total length from tip of 

 rostrum to end of caudal pleopoda 32 to 39 mm. 



This species, which was sent me by Professor A. J. 

 McClatchie of Throop University, is stated by him to be 

 common in the streams about Pasadena, California. This 

 species differs from O. multidentata, serrata, acuminata, 



