58 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



cent genera have a closed (viz. Dreissena and Modiolarca) and which 

 have an open mantle (Modiola, Mytilus). 



Description of New Species. 



In conclusion, I am desirous of noticing a few species of Hippurite 

 and Radiolite which appear to be new, or hitherto insufficiently de- 

 scribed ; the species are in the British Museum. 



1. Hippurites Loftusi, n. sp. PI. III. 



Shell inversely conical, or elongated : uppei^ valve convex, with 

 about twenty rounded ribs, of unequal length, radiating from the 

 centre ; pores very conspicuous, about one-third the diameter of the 

 ribs ; canals large, opening in a single series upon the inner margin : 

 lower valve furrowed and striated lengthwise ; ribs about twenty, ob- 

 scure, rounded ; cardinal side with a few prominent lines of growth ; 

 cardinal furrows three, distinct ; ligamental inflection deep ; dental 

 processes and pits placed across the interior. 



Length 4 inches and upwards ; diameter 2\ inches and more. 



This species belongs to the typical division of Hippurites, like 

 H. cornu-vaccinum, in which the teeth are placed at right angles to 

 the hinge-line. The pores in the upper valve are larger than in any 

 species I am acquainted with ; but, as names derived from comparative 

 characters are inadmissible, I propose to call this fossil after its dis- 

 coverer, Mr.W. K. Loftus, who obtained it with the three following 

 species from a limestone in the Bakhtiyari Mountains on the Turco- 

 Persian Frontier. 



2. Hippurites colliciatus, n. sp. PI. IV. fig. 5. 



Upper valve unknown : loiver valve conical, furrowed lengthwise 

 by about twelve unequal rounded channels, divided by prominent acute 

 ribs ; cardinal side flattened, with a small rib in the furrows opposite 

 the inflections ; shell-wall thick (3-6 lines), with two short and thick 

 inflections ; no ligamental inflection ; inner shell-layer thickened in 

 the cardinal region, and perforated by two dental pits close to the 

 side. 



Length 3 inches, diameter 3 inches. 



This species agrees with H. oculatus and radiosus in having the 

 interior divided by only two duplicatures, and in the dental pits 

 being close to the shell -wall in front of the adductor inflection. 



Locality : Bakhtiyari Mountains. 



3. Hippurites corrugatus, n. sp. PI. IV. fig. 4. 



Upper valve unknown : lower valve nearly cylindrical, with about 

 ten deep longitudinal furrows, divided by rounded corrugations, each 

 with several small ridges and striae, slightly tuberculated, and squa- 

 mose with lines of growth ; interior furrowed lengthwise ; ligamental 

 inflection angular. 



