219 



4 BELLEROPHON SEMISCULPTUS. PI. XVIII, fig. 5. 

 Bull. Nat. Hist. Soc. of N. Brunswick, vol. iv, p. 410, pi. xviii, fig. 5. 



Only the last whorl khown. This is free from the inner part of the Bellerophon 

 coil. The proximal part is smooth with faint concentric. undulations of 8emi8Clll i ttU8 - 

 growth. 



The lines of growth arch backward toward both ventral and dorsal 

 side, and at the dorsum there is an elevated flattened keel, separated from 

 the lateral slopes by a slight furrow ; the striae that run backwards to 

 this keel traverse it at right angles. 



Sculpture. The outer two-thirds of the whorl is marked by sharp- 

 edged, concentric ridges of growth ; at first there are about four in the 

 space of a millimetre, then they become more distant with flattened spaces 

 between, and toward the orifice of the shell there are about two ridges in 

 the same space. Between the ridges, and on the smooth part of the 

 whorl, the surface of the shell is minutely granulated. 



Size. Only one example is known, which is 7 mm. across from the 

 back of the whorl to the mouth, and 6 mm. across from the ventral side 

 of the mouth to the dorsal keel. 



Horizon and locality. In fine gray shale of Assise C. 3 c- at McLeod 

 brook, Boisdale, N.S. 



This species r3sembles B. hippopus, Salter, of the Arenig horizon in Compared. 

 Wales. It differs in its smaller size and in the very regular ridges of 

 growth, there being no alteration of weak and strong ridges. From B. 

 arfonensis, of the same author, it differs in the raised keel in place of a 

 depressed band along the dorsum. 



OSTRACODA. 



BEYRICHIA TRICEPS, n. sp. Plate xvi, figs. 4 a to c. 



Form sub-semicircular, about one-third longer than wide. Hinge line Beyrichia 

 straight, nearly the length of the valve ; valve somewhat oblique, the 

 anterior marginal slope being straightened, posterior cardinal slope short, 

 anterior wanting ; valve slightly pointed at the ventral edge. Surface 

 raised in three tubercles toward the hinge line ; of these the anterior 

 becomes a high narrow ridge, close to the anterior margin, and about 

 half as long as the width of the valve ; it is highest in the middle of its 

 length, where it is crowned by a small (ocular ?) tubercle ; one example 

 shows several colored spots (in place of one, which is usual) on the mould, 

 along this ridge. There is a narrow marginal fold around the edge of 

 the valve, except at the hinge. 



