A. IT. Foord and O. C. Crick — On Temnocheilus coronatiis. 297 



cannot be any doubt as to their identity. But Mr. Garwood's 

 specimens (there are two) are in such a fine state of preservation, 

 and probably nearly, if not quite, mature, that they enable us to add 

 somewhat even to M'Coy's amended description of the species. 

 One specimen has a diameter of 125 mm. ; the other, the inner 

 whorls of which are represented in the accompanying figure (the 

 outer being omitted to save space), was somewhat larger. 



The shell consists of rather more than three vv^horls, and there 

 is a central elliptical vacuity whose diameters are 10 and 7 mm. 

 respectively. The septa are about 10 mm. apart on the periphery, 

 where the shell has a diameter of 90 mm. The ornaments consist 

 of a row of tubercles situated at the junction of the umbilical and 

 peripheral borders. Beginning at about the mid-length of the first 

 whorl as obscure undulations, the tubercles gradually increase with 

 the growth of the shell, until at about the second whorl they have 

 become large and prominent. They are of a flattened conoidal 

 form and slightly elongated longitudinally. There are fourteen 

 tubercles per whorl in an adult shell. The test is thin, its surface 

 marked with fine strias of growth, forming an obscurely sigmoid 

 curve upon the sides, and bent backwards in a deep sinus on the 

 periphery, where they become much coarser in the adult shell, 

 especially in crossing the tubercles (see Figure). The ornamen- 

 tation of the young shell is that which is characteristic of most, if 

 not of all, of the coiled Nautiloids, including the recent Nautilus, 

 viz. fine longitudinal raised lines, crossed by still finer ones, and 

 thus forming a beautiful cancellated structure. The transverse 

 lines become obsolete before the end of the first whorl, but the 

 longitudinal lines die out at about the end of the first fourth of the 

 second whorl, among the last to disappear being two lines just 

 below the tubercles. 



Some differences are observable between M'Coy's type and the 

 Yorkshire form, the peripheral area in the former being a little 

 wider than that of the latter, and the sides of the umbilicus rather 

 steeper ; the tubercles also are more flattened than they are in the 

 English fossil. These differences, however, may be rightly attri- 

 buted, we think, to the distortion undergone by M'Coy's specimen, 

 the lateral pressure having widened the periphery, while at the 

 same time altering the true form of the umbilical region. M'Coy's 

 figure (pi. iv. fig. 15) represents a more perfect specimen than the 

 one from which it was drawn, unless the latter has since been 

 damaged. The only species with which M'Coy, when describing 

 his species, compared it is the Nautilus [^^Coelonautilus^ cariniferus^ 

 of J. de C. Sowerby, tuberculated species of the group now called 

 Temnocheilus being probably rare at the time M'Coy wrote. But in 

 his "British Paleeozoic Fossils" (p. 558), M'Coy in referring to this 

 species says : " This exceedingly rare species is distinguished com- 

 pletely from the N. tuberculatus ^ by the great thickness, or width, 

 of the mouth as compared with the diameter, the much more rapidly 



1 J. de C. Sowerby, Min. Con. vol. v. p. 130, pi. cccclxxxii. fig. 3 (excl. fig. 4). 

 * J. Sowerby, Min. Con. vol. iii. p. 90, pi. ccxUx. fig. 4. 



