BOTIIRIOLEPIS CRISTATA. 1;}] 



Fig. 3 shows the impression of the ventral surface of the cai-apace and of the 

 left pectoral appendage, an internal mould of the greater part of the right 

 one being also present. The imprints of the flat inferior portions of all four 

 ventro-lntend plates are seen, also the respective positions of the semilunar plate 

 (,s-. /..) and of the small lozenge-shaped median ventral. Owing to the oblique 

 squeeze to which the body has been subjected, the lateral portions of the right 

 anterior and posterior ventro-lateral plates are also seen in impression. The 

 pectoral appendages, neither of which is complete, must have, judging from what 

 remains of them, attained a length equal to the distance between the pectoral 

 articulation and the posterior extremity of the ventral aspect of the carapace. 

 I observe no evidence of denticulation on their outer margins. 



Fig. 4 is one of the two specimens collected by Mr. Taylor, and shows the 

 impression of a portion of the dorsal aspect of the carapace represented by portions 

 of the following plates: anterior median dorsal (a.m.d.), yosterior median dorsal 

 {p. m. d.), left anterior dorso-lateral (a. d. I.), and left posterior dorso-lateral (jj. d. /.). 

 Crossing obliquely that hinder portion of the anterior median dorsal plate which 

 is shown in this fragment, the left line of the V-shaped dorsal sensory groove is 

 seen, but the great feature of the specimen is the impression of the median crest 

 in the form of a deep cleft placed along the mesial line of the posterior part of the 

 plate and the anterior part of the posterior median dorsal. The very same 

 feature being shown quite as clearly in the second specimen, also the impression of 

 a portion of the back, which the Edinburgh Museum owes to Mr. Taylor, and the 

 two being compared with Dr. Gordon's original example, there can be no doubt as 

 to the existence of the remarkable feature which led me to establish the species 

 cristata on the above described material. The external sculpture of the jjlates in 

 all three specimens has the same fine tuberculo-reticulate character. 



Remarks. — The singular median dorsal crest distinguishes this species from all 

 other members of the genus Bothriolepis. 



If the nearly entire specimen represented in Figs. 1 and 2 on PI. XXXI seems 

 to denote an Asterolepid of a more narrow and elevated contour of body than is 

 indicated by the fragment of the dorsal surface shown in Fig. 4, I rather think 

 that that is due to lateral compression in the former case, and not to specific 

 distinction. 



Geological Position and Localiti/. — The species is known only from the Upper 

 Old Red Sandstone of the Rosebrae Quarry, near Elgin. 



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