Remai'ks on the Trilobites. 39 



writers have applied to it the term calymene macrophthalma, first 

 given by Professor Brongniart, not only to this fossil, but to an- 

 other, which differs essentially from it. He has given in his 

 admirable work on this subject good figures of both animals, but 

 his specific description refers only to plate 1, figure 4, A. B. He 

 observes, "that the species is remarkable by the prolongation of 

 the anterior portion of the buckler in the form of a snout, and that 

 its middle lobe, or front, is marked on its sides by three oblique 

 flicm or wrinkles, like those on the C. tristaMV This descrip- 

 tion applies very well to some reliques found in the Dudley rock, 

 which we have examined, but it is perfectly obvious that the cal- 

 ymene bufo, which has a rounded front, and is entirely destitute 

 of plicae or wrinkles, cannot be included in it. We therefore 

 took the liberty in our little work of calling by the name of caly- 

 mene bufo, the fossil represented on his first plate at figure 5, and 

 which is so common in the United States ; and of restricting the 

 C. macrophthalma to the animals represented on the same plate at 

 figure 4, which are specifically distinct, and if not so called, must 

 still remain nameless. 



Note. — Mr. Murchison in his magnificent work styled the Silurian System, has 

 proposed the name of calymene Downingife for one of Professor Brongniart's fos- 

 sils, called C. Macrophthalma, and restricts the terra Macrophthalma to the one 

 which I have named Calymene Bufo. There are several objections to this no- 

 menclature. 1st, The C. Macrophthalma, Brong. was long ago divided into two 

 species by me for the reason above stated. 2d, In M. Ach'ille Comptes large pic^ 

 torial illustrations of the Regne Animal, the C. Macrophthelma is represented by 

 Brongniart's figure 4, A. B. ; naturalists therefore already know it under that name.. 

 The following are Mr. Murchison's remarks on this subject : " I have separated 

 the C. Macrophthalma, Brong. into two species, believing that his figure plate 1, 

 figure 4, B, is our common large eyed species, and that his figure 4, A, of the 

 same plate, judging from the ovate, accuminate head and the tubercles on the fore- 

 head is our C. Downingiae. The last mentioned species is infinitely rarer than 

 that to which I would restrict the name of Macrophthalma. That species is at 

 once recognized by its bald, plain, rounded head, as is well exposed in the draw- 

 ings of Mr. Stokes. See Brong. plate 1, figure 5, A, B, C. I have named this spe« 

 cies after Mrs. Downing, to whom I am indebted for the loan of it." 



