No. 26.] ARTHROSTRACA OF CONNECTICUT. 227 



to 25 fathoms, and is always concealed by an adhering layer of 

 mud. 



It is distinguished from the preceding species by the more 

 rounded lateral margins of the body, the different form of the 

 abdomen, and the absence of tubercles on the lateral portions 

 of the thoracic segments. 



Erichsonella attenuata (Harger). 



Erichsonclla attenuata. 



1874. Erichsouia attenuata, Harger, Rept. U. S. Com. Fish. 

 for 1871-2, p. 570, pi. 6, fig. 27. 



1880. Erichsouia attenuata, Harger, ibid., for 1878, p. 356, 

 pis. 6 and 7, figs. 36 and 37. 



1905. Erichsonella aitenuata, Richardson, .Bull. U. S. Nat. 

 Mus., No. 54, p. 400. 



Body narrow, elongate, about five times as long as wide ; 

 abdomen one-fourth as long as entire body. Surface of body 

 smooth throughout. Head wider than long with anterior margin 

 slightly excavate between the prominent antero-lateral angles, 

 with a prominent elevation between the eyes, which are small, 

 compound, and situated half way between anterior and posterior 

 margins of the head on the lateral margins. 



First pair of antennae with first joint large and dilated ; second 

 joint a little shorter than the first and half as wide; third and 

 fourth joints subequal in length and each one and a half times as 

 long as the second; extending slightly beyond the second joint 



