480 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



frontal margin smooth and slightly curved, with a small incision at the 

 center. Dorsal surface of the carapace with well-defined grooves 

 marking it oft" into areas similar to those in the Pandaringe. The two 

 longitudinal grooves are strongly concave toward each other, like 

 parenthesis marks, the space between them being nearly two-thirds of 

 the entire width. The lateral areas outside of these grooves are wider 

 posteriorly, and are prolonged backward on either side in a large lobe 

 which extends nearly to the anterior margin of the dorsal plates of the 

 fourth thorax segment. Each of these lateral areas is divided by a 

 transverse groove which starts from a deep sinus in the lateral margin 

 and curves inward and backward to the longitudinal groove. The 

 posterior. or thoracic portion of the area is thus shorter but wider than 

 the anterior portion, and has somewhat the appearance of a lateral 

 plate attached to the posterior portion of the carapace. 



The second and third thorax segments are fused together and fur- 

 nished with a" single pair of lateral plates, one on either side beneath 

 the posterior carapace lobe and nearly concealed by it. The fourth 

 thorax segment is considerably narrower than the second and third, 

 but carries a pair of large dorsal plates which extend outward on 

 either side to a level with the lateral margins of the carapace and back- 

 ward until they overlap half the genital segment. The two plates are 

 entirely fused anteriorly for about one-quarter of their length; the 

 combined anterior margin is a nearly perfect arc of a large circle 

 which terminates at either end in a short and sharp spine. Each plate 

 is nearly circular in outline and is bordered by acuminate spines simi- 

 lar to those on the carapace, but not quite as large. 



The sinus between the plates is wide and well rounded at the base, 

 but farther back its sides approach until they are in actual contact. 

 The combined dorsal plates of the fourth and genital segments are 

 about the same size as the carapace, and inversely the same shape. 

 As the abdomen is hidden, this gives the copepod a regular elliptical 

 outline, broken across the short diameter by the waist between the 

 carapace and fourth segment. 



The joint between the third and fourth segments seems to be the 

 only one which is really flexible, and the anterior half of the body is 

 frequently folded over ventrally against the posterior half. The dor- 

 sal surface of the genital segment is also covered by a pair of plates 

 similar to those on the fourth segment and finely serrate around the 

 margins. The posterior sinus between these plates is deeply cut and 

 is similar to that between the fourth segment plates. 



The abdomen is of medium size, considerably wider than long, and 

 unsegmented ; it is attached to the ventral surface of the genital seg- 

 ment just in front of the base of the sinus, between the dorsal plates of 

 the latter. Its own posterior margin is slightly reentrant on either 

 side where the lamina is attached; these laminae are small, foliaceous, 



