CERATIOCARIS SALTERIANA. 55 



23. Ceratiocaeis Salteriana, T. E. J. Sf H. W., 1885. PL VII, figs, la, 1 b, 2, 3. 



1885. Ceratiocaeis Saltebiana, T. R. J. & H. W. Third Eeport Pal. Phyll. 



Brit. Assoc, p. 348 ; 



Geol. Mag., 1885, p. 462. 

 1886 — — Fourth Eeport, p. 231 ; 



Geol. Mag., 1886, p. 458. 



Four specimens, in rather different states of preservation, from the Lower- 

 Ludlow strata, indicate the existence of a distinct species of Ceratiocaris, having 

 nearly oblong carapace-valves, with almost equally rounded ends, and ornamented 

 with delicate but distinct horizontal parallel lines, rather wide apart. 



One of these, a carapace, M. P. Gr. d yf a, 1 & 2, from Bow Bridge, Ludlow, 

 well preserved, is 30x15 mm., straight on the back, rounded at the ends. The 

 two counterparts are here figured, figs. 1 a, 1 b. 



In very fine-grained, grey, micaceous, and partly calcareous mudstone, break- 

 ing unevenly, are the two light-brown, suboblong valves, one shifted on the other, 

 and more or less buried in the matrix at the dorsal edge ; smooth, with delicate, 

 parallel, longitudinal striae, a centimetre apart where broadest, running closer to 

 each (some dying out) near the ventral margin. Marginal rim strong and narrow. 



The transverse markings are of mechanical origin, being due to small narrow 

 patches of the test remaining alongside of numerous obliquely-transverse cracks. 



In fig. 1 a, d ff a 2, the right valve is uppermost, but is only partly seen, 

 its dorsal edge and both of its angles being lost in the matrix. [The antero- 

 ventral curve is rather too bold in the drawing.] The raised striae are seen on the 

 upper left-hand portion (posterior third of the right valve), one centimetre apart, 

 and ending abruptly in the posterior rim. 



The lower part of the specimen is the inside of the left valve, with sunken 

 striae on the inner face of the test. 



Fig. 1 b, d ff a 1, is the counterpart of two-thirds of the compressed carapace. 



In the Cambridge Museum, a/694 (Fletcher Collection), marked " Dudley ; in 

 upper shale," which is a dark-grey, very fine-grained, and slightly calcareous 

 mudstone, of the Lower Ludlow formation, is a similar carapace (PI. VII, fig. 2), 

 nearly as well preserved as fig. 1, and measuring 30 X 13 mm. It is mentioned by 

 Salter in the ' Catal. Camb. and Sil. Fossils Mus. Cambridge,' 1873, p. 129. 



The ventral margin has a distinct raised rim. The striae and interspaces differ 

 in tint of colour on the cast. Some internal organs (teeth ?) have caused a little 

 break or hole, and a derangement of the striae in the antero-dorsal region. The 

 valve is suboblong. The hinder margin has a slight ogee curve ; the front is 



