164 Mr. G. B. Sowerby on 



the antennae are unfortunately imperfect, there being - only 

 twelve joints on the left flagellum and ten on the right one, 

 Miers gives the numbers as 14 to 24, but, even with the 

 addition of the missing joints, I think he has overstated the 

 length. 



The antennules are short and slender, extending slightly 

 beyond the antepenultimate peduncular joint of the antennas. 

 The second joint of the antenna? is deeply grooved laterally, 

 and the fourth and fifth joints elongated and subequal. 



The mouth-parts have not hitherto been described or 

 figured. The maxillae present no special features. The 

 maxillipedes are thin and flattened, in consequence of which 

 the fourth joint does not move in a groove on the anterior 

 border of the third joint, a character I have found in various 

 stages of development in quite a large number of species of 

 this genus, but, curiously, not mentioned in any of the 

 descriptions, so far as I am aware. 



I. hectica belongs to that division of the genus Idotea 

 which is characterized by the narrow, elongated, filiform 

 body, and in which the epimera are either not visible dorsally 

 or else are very small, and contains such species as I. linearis 

 (Linn.), /. indica, M .-Ed wards, and 2. elongata, Miers. 



EXPLANATION OF PLATE IX. 



Fig. 1. Dorsal view. 



Fig. 2. Antennule. 



Fig. 3. Peduncle of antenme. 



Fig. 4. First maxilla. 



Fig. 5. Second maxilla, terminal portion. 



Fig. 6. Maxillipede. 



Fig. 7. Left uropod. 



XXIII. — Descriptions of new Species of Mollusca from 

 various Localities. By G. B. SOWERBY, F.L.S. 



[Plate X.] 



Drillia parciplicata, sp. n. (PI. X. fig. 1.) 



Testa elongato-acuminata, sordide albida ; spira elongata ; an- 

 fractus 7, primus rotundatus, secundus planato vix convexus, 

 sequentes convexi, obtusissime angulati, oblique parci-plicati, ad 

 suturam leviter concavi ; anfractus ultimus oblongus, convexus, 

 fere laevis, a longitudinis testae aequans. Apertura oblonga, lati- 

 uscula ; labrum acutum, leviter iutiexum, posticelate et profunde 



