Part of Gloucestershire and Somersetshire. 327 



the animal that I have met with^ agree perfectly with the description given by 

 that author, and a few of them display the oculiform prominence, commonly 

 denominated the eye, in a tolerably distinct manner. 



Of the third species of trilobite, which I believe to be a non-descript, I have 

 only found specimens which exhibit separately the right and left lobes of the 

 head ; the most perfect of them extending only to the oculiform protuberance, 

 which last is much more elevated than in the two preceding species. Both of 

 the lateral lobes are accompanied by a coriaceous or membranaceous border, 

 which bears a double row of tubercles ; each tubercle of the inner, and 

 larger row, being of an oval form and prominent, while the outer tubercles 

 are circular, faintly expressed, and placed close to the edge between the 

 intervals of the larger. Each of the lateral lobes or cheeks, which supports 

 the high oculiform projection (and between which and the coriaceous border 

 is a longitudinal depression), is also provided with a double row of tubercles 

 nearly equal in size to each other, and placed below the eye parallel to the 

 external border. From the general disposition of the parts, it is probable that 

 the membranaceous border is continued around the central lobe of the head 

 also ; but I have never succeeded in developing a complete head, the materials 

 being very fragile : nor have I observed any other portion of a trilobite that 

 might be thought to appertain to this species. 



The fourth and last species of trilobite is the Calj/mene of Blumenhach 

 (Brongniart, PI. I. fig. 1.), of which, however, I can merely record two speci- 

 mens, each presenting only a considerable portion of the head, which I found 

 in Long's quarry, adjacent to Charfield-green. In the same quarry, which 

 yields some of the most distinct organic remains that occur in the Tortworth 

 district, are to be met with also the other trilobites just described *. 



hemispherical form, placed in the middle of the central lobe ; each tubercle being opposite to the 

 alternate transverse folds or articulations of the lateral lobes. The articulations of the centra! 

 lobe are merely marginal, being in number to those of the lateral lobes as three to two ; two of 

 the former corresponding with the latter, and the third being placed opposite to the interval 

 between the folds of the lateral lobes. Each of the latter articulations is also generally provided 

 with an ilUdefined tubercle adjacent to the central lobe. I thought the preceding description 

 might be useful, as the figure given by M. Brongniart but faintly expresses this part of the 

 subject. 



* The trilobites most commonly found at Dudley, are the Calymene of Blumenbach, and the 

 Asaphus caudatus; the Calymene variolaris appearing to occur there very seldom. But the Caly- 

 mene macrophthalma (Brongniart, PI. I. fig. 5.), for which the only locality given by that 

 author is Colebrookdale, is met with also at Dudley, though rarely, and likewise at Lincoln's 

 hill in Shropshire ; having been found in both those localities by my friend the Rev. Dr. Cooke, 

 Rector of Tortworth. 



VOL. VI 2 u 



