RENSSELL^RIA. , 45 



MOLLUSCOIDEA. 



1. CLASS BRACHIOPODA, Dumeril, 1806. 



1. ORDER ARTICULATA, Deshaijes, 1836. 



I. Family TEREBRATULID.E, King, 1846. 



1. Genus RENSSELLJIRIA, Hall, 1859. 

 1. EENSSELL^RIA ? FORMOSA, n. sp. Plate XVII, figs. 79. 



Description. Dorsal (?) valve elongate, convex, suboval, without a fold. 

 Surface covered by about twenty low, close-set, flatly rounded ribs, which do not 

 divaricate, but gradually increase in size from the umbo to the margins. Two 

 lofty median septa, continued a short distance forward from the umbo, sub- 

 parallel and not united, possibly supporting the hinge-plate, and surrounded by a 

 low ovoid ridge, which starts near the umbo, and, passing just in front of them, 

 may perhaps define a muscular area. Dental sockets lateral, triangular. Shell- 

 structure very minutely and regularly punctate. 



Size. A slightly crushed valve is 26 mm. long, by 16 mm. wide, and 7 mm. 

 deep. 



Localities. Four specimens from Ashford Strand are in my Collection, and 

 two from Pilton and Poleshill in the Porter Collection. 



Remarks. These specimens are all more or less imperfect. The first one dis- 

 covered (fig. 7) had assumed almost the exact shape and appearance of 

 Tropidoleptus carinatus (Conrad), and consequently I catalogued it as that shell. 

 Further examination, and comparisons on the one hand with our Ashford speci- 

 mens, and on the other with Davidson's figured specimens of T. carinatus, and 

 with German specimens kindly lent me by Mr. Upfield Green, have proved that its 

 umbonal arrangements agree with the former and not with the latter, and that 

 the specimen owes its peculiar shape to excessive distortion. It therefore is 

 proved not to be T. carinatus, and that species does not occur in the Pilton Beds. 



The best of my specimens from Ashford appears to afford considerable informa- 

 tion about this species, which is evidently beautiful and interesting, but perplexing 

 withal. Externally it might well be referred to Renssellserm, but I cannot satisfac- 

 torily correlate what is seen of the internal details with those given by Hall for his 



