ISOPODS 



217 



filiform, the thoracic segments subquadrate, head quadrate. He refers 

 to the Hnear post-abdomen, which is truncated at the apex, tliree- 

 jointed, and marked on either side with a suture. The antennae are 

 described as being a little shorter than half the body, with a ten- to 

 twelve-jointed flagellum. 



No figure of the form has ever been given. 



A species of Idotca was sent to the U. S. National Museum by Dr. 

 Ritter. The specimens, which are eight in number, were collected by 

 him at Bolinas, California. They are more closely allied to /. p-acinif?ia 

 than to any other known species of Idotea from the Pacific coast of North 

 America. Until evidence can be given of their distinctness, I shall con- 

 sider them identical with /. gracillbna (Dana). 



Body slender, about seven times longer than wide,^ with the sides 

 nearly parallel. Surface entirely smooth. Color in alcohol uniformly 

 pinkish. A note referring to the color of the specimens in hfe states that 

 they are green, brown, and striped. 



Head quadrate, with rounded antero-lateral margins, and a slight 

 median excavation in the anterior margin. Eyes situated at the extreme 

 lateral edge and about the middle of the 

 head ; they are small but distinct. The 

 first pair of antennae are four-jointed, and 

 extend a little beyond the extremity of 

 the second peduncular joint of the second 

 pair of antennae. The second pair of an- 

 tennae are equal to half the length of the 

 body ; the last two joints of the peduncle 

 are subequal ; in the smaller specimens 

 the flagellum is composed of ten joints ; 

 in the larger ones there are eighteen joints. 



The first thoracic segment is short in 

 the middle but is produced antero-later- 

 ally on either side ; it is not wider than 

 the head. The second, third, and fourth 

 segments are subequal in length and are Fig. 97. idoteu sraciiuma (D^v,t>) ix i). 

 longer than the first segment. The fifth, sixth, and seventh segments 

 gradually decrease in length. The epimera of all the segments are ex- 

 tremely narrow ; those of the second and third segments extend but half 

 the length of the segment ; those of the fourth and fifth segments extend 

 three fourths the length of the segment ; those of the last two segments 

 extend the entire length of the segment. 



iThe female is figured. The boJy is somewhat broader than in the male. 



