118 

 TRIGONTA INCURVA, Benett, plate iii., fig. 1. 



MONO. BEIT. Foss., TEIGONLE, Lye., Pal. Soc., p. 42, plate ix., figs. 2-6. 

 Damon's Geo. of Weymouth, Sup., pi. vii., fig. 1 

 (internal mould), 1880. 



Shell elongated, curved at the two extremities ; anterior side 

 convex ; posterior side lengthened, curved and depressed ; 

 umbones large, elevated, somewhat recurved, and placed near 

 to the anterior border, which is curved elliptically with the lower 

 border ; escutcheon concave, lengthened, its superior border 

 somewhat raised ; area narrow, distinctly, bipartite with three 

 delicate tuberculated carinse, and irregular transverse plications. 

 The ornamentation on the sides of the valve varies much in 

 accordance with the development in the growth of the shell. 



Obs. Trigonia incur va, passes from the Kimmeridge clays to 

 the Portland Limestones. It occurs at Kimmeridge Bay, and at 

 Portland ; the moulds are very common, but it rarely happens 

 that any considerable portion of the test is adherent. Dr. 

 Lycett's fig. 2 is from a specimen in my collection, from Kim- 

 meridge Bay, and is now in the National Museum of Practical 

 Geology, Jermyn Street. 



TRIGONTA WOODWARDI, Lye., plate iii., fig. 2. 



MONO. BEIT. Foss., TEIGONLE, Lye., Pal. Soc., p. 40, plate xvii., fig. 1. 



Shell large, ovately trigonal, depressed; umbones elevated, 

 pointed, recurved, placed at about the anterior third of the 

 valves ; anterior side produced, its border curved obliquely with 

 the lower border, which is lengthened, and nearly straight 

 posteally ; the superior border is nearly straight, sloping down- 

 wards obliquely, and forms only a slight angle with the posteal 

 border of the area, which is pointed at the lower extremity ; the 

 escutcheon is narrow, lengthened and concave, the border 

 raised; area narrow, its superior or umbonal portion forms a 

 considerable angle with the costated surface of the shell, of 

 which the rows of costse are small, widely separated, and nearly 



