370 AXATOIDiE. 



attenuate and gaping posteriorly. Hiuge composed of a 

 spoon-shaped cartilage-process projecting into the interior ; 

 cartilage internal, without any free ossicle. Muscular im- 

 pressions elongated; pallial line with a deep, angulated 

 sinus. 



Syn. Nesera, sp. Hinds. 



Ex. T. lata, Hinds, pi. 97, fig. 5, 5, a. 



Mr. Hinds, in his Monograph of Neiera, first indicated 

 this group. Alluding to the three species described by 

 him, he observes, that they " are aberrant, and hold the 

 same relations to Netera as Nucula arctica (Brod. and 

 Sow.) and its congeners do to that genus." The examples 

 of Theora already known were obtained from the Philip- 

 pines in from four to ten fathoms. 



Species of Theora. 



fragilis, A. Adams. lata, Hinds. 



iridescens, Hinds. opalina, Hinds. 



Genus PANDORA, Solander. 



Siphons very short, umted nearly as far as their orifices 

 which are divergent and fringed. 



Shell inequivalve, thin, closed, beaked behind, pearly 

 within; right valve flat, the other more or less convex. 

 Hinge with a primary tooth in each valve, with corresponding 

 cartilage-pits ; no free ossicle ; ligament internal. Muscular 

 impressions faint, rounded ; pallial line with a very slight 



sinus. 



Syn. Calopodinm, Bolten. Trutina, Brown. 



Ex. P. obtusa, Leach, pi. 98, fig. 1 . Shell, P. inrequi- 

 valvis, LinncBiis, fig. I, a, 1, b. 



