BEACHIOPODA. 



■lateral. Tongue narrow, ■with three pectinated plates in each 

 row. Jaws large and strong, margins without denticulationt.'. 

 This genus is closely related to Antiopa. 



J. iiYLLOBRAiq'CHirs, Alder and Hancock, 1863. 



Type, Proctonotus orientalis, Kelaart. India. 



Animal elongated, flattened on the back, angulated at the 

 sides, without a distinct cloak. Tentacles two, dorsal, longitudi- 

 nally folded, bifurcate above, non-retractile. Head produced 

 at the sides into angulated and folded expansions. Branchiee 

 leaf-like, with distinct foot-stalks, arranged in several rows 

 along the sides of the back and round the head in front. Anus 

 lateral. The tongue resembles that of Hsrmcea, 



CLASS lY.— BEACHIOPODA.* 



Family I. — TEREBiiATiiLrD^.+ 



Terebratula [see p. 363), 



Sub-genus, Hensselmria, Hall, 1859. 



Dedicated to the late Hon. Stephen Van Eensselaer. 



Examples, E. ovoides. Hall, Fig. 18 ; Terebratula strigiceps, 

 Eomer. 



Shell ovoid or suborbicular, without mesial fold or sinus; 

 beak prominent, acute, more or less 

 incurved; foramen terminal, some- 

 times concealed. Ventral valve with, 

 two diverging cardinal teeth supported 

 by strong dental plates. Dorsal valve 

 with the dental sockets between the 

 shell and a strong process from which 

 the slender crura proceed, first in a 

 direct line, and then one division of 

 each, diverging into the centre of the 

 ventral valve, terminate in acute points. 

 On the other side the divisions extend 

 nearly at right angles to the axis of 

 the shell into the cavity of the dorsal 

 valve ; and thence bending abruptly 

 forward and gradually converging, The interiorStoe dorsal valve 

 terminate above the centre of the shell of R. ovoides, showing the thick- 

 J.1 • n ±1. J 1 -J. T n ened processes at the beak, th<^ 



m a thm flattened or longitudinally crura, the loop, and the narrow 

 concave plate. longitudinal plate. 



See p. 354. 



t See p. 363. 



63 



