UPPER AND LOWER. Ill 



The earliest aiscovered vertebral remains of the system, 

 — those of the Upper Ludlow rock, — were found in digging 

 the foundations of a house at Ludford, on the confines of 

 Shropshire, and submitted, in 1838, by Sir Koderick Mur- 

 chison to Agassiz, through the late Dr Malcolmson of Madras. 

 I used at the time to correspond on geological subjects with 

 Dr Malcolmson, — an accomplished geologist and a good man, 

 too early lost to science and his friends, — and still remember 

 the interest which attached on this occasion to his communi- 

 cation bearing the Paris post-mark, from which I learned for 

 the first time that there existed ichthyic fragments greatly 

 older than even the ichthyolites of the Lower Old E-ed Sand- 

 tone, and which made me acquainted with Agassiz's earliest 

 formed decision regarding them. Though existing in an ex- 

 ceedingly fragmentary condition, — for the materials of the 

 thin dark-coloured layer in which they had lain seemed as if 

 they had been triturated in a mortar, — the ichthyologist suc- 

 ceeded in erecting them into six genera ; though it may be 

 very possible, — as some of these were formed for the recep- 

 tion of detached spines, and others for the reception of de- 

 tached teeth, — that, as in the case of Dipterus and Asterolepis, 

 the fragments of but a single genus may have been multiplied 

 into two genera or more. And minute scale-like markings, 

 which mingled with the general mass, and were at first re- 

 garded as the impressions of real scales, have been since re- 

 cognised as of the same character with the scale-like markings 

 of the Seraphim of Forfarshire, a huge crastacean. Even ad- 

 mitting, however, that a set of teeth and spines, with perhaps 

 the shagreen points represented in page 27, fig. 2, 6, in addi- 

 tion, may have all belonged to but a single species of fish, 

 there seem to be materials enough among the remains found, 

 for the erection of two species more. And we have evidence 

 that at least two of the three kinds were fishes of the placoid 

 order (Onchue Murchisoni^nd Onchus tenuistriatusj, and — 



