116 



MOLLUSCA. 



Spirifek. 



Smooth, subcordiforra ; beaks greatly incurved ; base some- 

 what produced. 



Carboniferous Limestone, Bildwas, Shropshire. 



4. Gypidium galeatum The Helmet Gypidium, pi. 



XLIX. fig. 44, 45. 



Atrypa galeata. Sowerby, Sil. Syst. p. 618, pi. 8, fig. 10, 

 and pi. 11, fig. 4. Dalm. 1. c. p. 130, pi. 5, fig. 4. 



Nearly globular, longitudinally furrowed, crossed by distinct 

 lines of growth; base somewhat depressed in the centre; larger 

 valve very deep, with a large, rounded, incurved umbo, termi- 

 nating in a blunted beak ; lesser valve convex. Diameter four- 

 teen lines; depth of each valve half an inch. 



Found in the Wenlock Limestone at Westhope, Wenlock 

 Edge, near Amestry, and Lower Ludlow Rock. 



5. Gypidium oblongum The Oblong Gypidium, pi. 



XLIX. fig. 46, 47. 



Pentameris oblongus. Sowerby, Sil. Syst. p. 641, pi. 19, 

 fig. 10. 



Depressed, oblong-ovate, smooth ; beak of larger valve pro- 

 duced, with sometimes a few shallow furrows on the surface ; 

 margin of valve undulated by the furrows, without deviating 

 from the same plane. Length two inches and three-quarters ; 

 width two inches and a quarter. 



Found in the Cardock formation, the Hollies, Soudley and 

 Norbury, Salop ; Castell Craig-gwyddon, Llandovery. 



Genus V MAGUS Sowerby. 



Shell inequivalve, equilateral ; one valve convex, pro- 

 vided with an angular sinus along an incurved beak; line 

 of the hinge and back of the other valve straight, with 

 two projections near the centre ; a partial longitudinal 

 septum attached to the hinge within. 



I. Magus pumilus. — The Dwarf Magus, pi. XLIX. fig. 5 

 and 13. 



Magus pumilus. Sowerby, II. p. 40, pi. 1 19, fig. 1 to 5. 



The beaked valve spherical, smooth, with its edge circular ; 

 beak small, straight, and slightly incurved at the point ; flat 

 valve quite depressed ; the hinge line long, and parallel ; outer 

 surface beset with numerous, very minute punctures, disposed 

 ill a quincunx order, which, however, are indistinct without the 

 aid of a lens. 



Found in the Chalk near Maudesley, Norwich. 



Genus VL— TRIGONOSEMUS— J^o«?>. 



Shell inequilateral, subtrigonal ; one valve generally 

 more convex than the other; one of them prolonged into 

 a lengthened beak, truncated at the point, and perforated 

 for the passage of a tendon, by which the animal attaches 

 itself to extraneous substances ; hinge destitute of a 

 ligament, but provided with two teeth in one valve, 

 which lock into corresponding cavities in the other ; two 

 muscular impressions, situate near the centre of both 

 valves. 



Konig, Icon. Foss. Sci. p. 



76. Te; 



1. Trigonosemus LYRA. — The Lyre-formed Trigonose- 

 mus, pi. LIL* fig. 11. 



Trigonosemus Lyra, 

 hratula Lyra, Sowerby, II. p. 87, pi. 138, fig. 2. 



Elongated; the upper valve equal to double the width of the 

 shell ; beak of lower valve much elongated, and containing two 

 longitudinal septa ; that of the upper valve short, and incurved ; 

 surface with divergent, furcated plaits, crossed by inequidistant, 

 remote lines of growth. 



Found in the Upper Greensand at Chute Farm, near Hor- 

 ningsham, Warminster, and Blackdown. 



Genus VIL— STRIGOCEPHALUS.— Z)f//-a«ce. 



Lesser valve suborbicular ; larger valve extending be- 

 yond it, into an elongated, acute angled, incurved beak ; 

 foramen situate on a broad, flattened, and sharply bor- 

 dered area, striated lengthways and across. 



In the more adult condition the triangular foramen is 

 partially contracted with shelly matter, and presents a 

 round perforation, which is finally closed. 



1. Strigocephalus brevirostri. — The Short-beaked 

 Strigocephalus, pi. LII.* fig. 5. 



Strigocephalus breverostris, Phillips, Pal. Fos. p. 80, pi. 

 32, fig. 143. 



Tumid, smooth, suborbicular ; lesser valve nearly orbicular ; 

 the larger one extending beyond it into a short, incurved umbo, 

 ending in a tumid beak; beneath which is an acute, broad fora- 

 men, which receives the beak. 



Found in the Devonian Shale, South Devon, Plymouth, and 

 Newton. 



2. Strigocephalus porrectus The Extended Strigo- 

 cephalus, pi. LIL* fig. 6. 



Terehratula porrecta. Sowerby, VI. p. 147, pi. 576, fig. 1. 



Subquadrangular, convex, smooth, with rounded angles; beak 

 of larger valve considerably produced and subacute, and slightly 

 curved; area large, margin acute; perforation situate within the 

 apex. 



This species differs from S. Burtini in the beak being straighter, and 

 the shell more quadrangular. 



Found in the Carboniferous Limestone at Bradley. 



3. Strigocephalus giganteus. — The Gigantic Strigoce- 

 phalus, pi. LIL* fig. 12, 13. 



Strigocephalus giganteus. Sowerby, Geo. Trans, pi. 56, fig. 

 10, 11. Phillips, Pal. Fos. p. 80, pi. 32, fig. 142. 



Smooth, convex, suborbicular ; valves nearly equal ; beak of 

 larger valve straight, and pointed; beneath which is a rectangu- 

 lar-triangled, flat area; foramen narrow. 



Found in the Devonian Shale at Plymouth and Newton 

 Bushel. 



4. Strigocephalus Burtini Burtin's Strigocephalus, 



pi. LIL* fig. 15, 16. 



Strigocephalus Burtini. Phillips, Pal. Fos. p. 79, pi- 31, fig. 

 141. Defiance, Die. des Sci. Nat. pi. 75. 



Subglobose, smooth, with a few obsolete lines of growth; 

 both valves much inflated, the lower one with a long, consider- 

 ably curved, somewhat acute beak; foramen long, wide, and flat 

 at bottom. 



