CYMODOCEA TRUNCATA. 427 



The body is somewhat cylindrical, with the sides nearly 

 parallel. The entire length of the animal is about two 

 and one-fourth times the width of the middle of the 

 body. The antennae are short, the inferior being about 

 as long as the breadth of the head ; the superior have 

 the basal joint (omitted in our upper left-hand figure) 

 strongly punctured. The tail has the upper surface 

 irregular and setose. The basal portion has the middle 

 of the posterior margin extended backwards, and emar- 

 ginate, with two small tubercles near the angles of the 

 emargination. The large terminal joint has two large 

 oval setose tubercles in the middle of the upper side, 

 followed by a slightly convex lobe, on which the bristly 

 setae are set in a diverging manner ; and the extremity 

 of the joint is armed with three flat truncated spines. 

 The lateral appendages of the tail do not close as in the 

 SpJueromcE, so as to form a convex shield, but are carried 

 obliquely upwards ; the inner division is small and 

 obliquely truncate, with the entire margin thickly set 

 with strong bristles, and the outer division is consider- 

 ably larger and oval in form, but with the outer angle 

 subacute. The inner portion of this outer plate is par- 

 tially folded when at rest beneath the inner plate. 



This species was taken by Montagu and Leach on the 

 Devonshire coast ; but very sparingly. The Rev. A. 

 Norman dredged it in Lamlash Bay, in the Isle of Arran, 

 and found it imder rocks at low water at Herm; and the 

 late Mr. W. Thompson took it in Belfast Bay, at Rock- 

 port, in April, and Mrs. Hyndman on Cultra shore, in 

 September, and Dr. Macintosh has sent it to us from 

 St. Andrews. 



