205 Mr. Lubbock on two new Subgenera of Calanidse. 



concentrically laminated ; beak acute, incurved, with a small 

 adherent area; larger valve extended laterally, inflated and 

 bilobed, having a wide and deep sulcation which extends from 

 the beak to the lower border ; upper valve concave ; margins of 

 the valves sinuated. 



The deep sulcation in the dorsal surface separates a posterior 

 lateral lobe, which in the mature form has a diameter equal to a 

 third part of the entire valve : in the young state the posterior 

 lobe is but slightly developed, and the valves at that part are 

 thin, but the groove is always conspicuous. 



The species which most nearly approach G. Buckmanni are 

 G. dilatata, Sow., and G. controversa, Roemer ; but these latter 

 are much larger species, they are less inflated, and have the 

 dorsal sidcation much more superficial. 



XIX. — On two new Subgenera q/" Calanidse. 

 By John Lubbock, Esq., F.Z.S. 



[With a Plate.] 



Among Mr. Darwin^s Crustacea, I discovered a few specimens of 

 a remarkable Entomostracan nearly allied to Labidocera Darwinii, 

 but dififering considerably from it in the structure of the right 

 antenna of the male, of the fifth pair of legs, and of the abdomen 

 of the female ; and lately, in the collection of the College of Sur- 

 geons, through the kindness of Prof. Owen and Prof. Quekett, I 

 found a single male specimen of a third very distinct species be- 

 longing to the same group, in which the right antenna of the 

 male is more anomalous than in any form yet described. These 

 two new species will, I believe, eventually form the type of two 

 new genera; for the present, however, it will perhaps be more 

 convenient to consider them subgenera of Labidocera. For this 

 purpose it will be necessary slightly to alter its generic character, 

 which will stand as follows : — 



Labidocera. 



Eostrum furcatum ; antenna antica maris dextra geniculaus 

 tumida, lamellis lobulisve dentatis instructa. Oculi superiores 

 duo. Oculi inferiores nuUi ? Cephalothorax 7-articulatus. Pes 

 posticus maris dexter, prehensilis. Abdomen maris 4-articulatum, 

 foeminse 2-articulatum. 



And will contain three subgenera : — 



