6 



[No- 7. 



Description of the Species, with Biological 

 Observations. 



Fam, Sididce. 

 Gen. Latonopsis, n. 



(see Plate I). 



Generic Characters. — General aspect very similar to that 

 of Latona, but no dorsal impression between head and trunk, and 

 no distinct fornicate plates laterally above the oral region. Shell- 

 gland very remarkable, tripartite, one of the branches passing 

 across the anterior part of the valves, another straight back- 

 wards along the sides, and the third upwards. Antennulae with 

 flagellum distinctly articulated to the basal part and not geni- 

 culate. Antennae with the upper branch biarticulate, first joint 

 simple, without any lamellar setiferous prolongation of the inner 

 edge. Heart very large, saccular, anteriorly truncate, posteriorly 

 rounded, upper edge concaved. 



Remarks. — By the above-given characters, this new genus 

 is readily distinguished from Latona. agreeing however in moi 

 of the other features very closely with that genus, the Austra- 

 lian representative of which it may be said to constitute. 



1. Latonopsis australis, n. sp. 



(Pi. l). 



Specific Characters. — $. Carapace oblong, height and breadth 

 about the same, slightly tapering towards the posterior extremity- 



