Remarks 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 
plice. or wrinkles, like those on the C. tristani.” 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 plice 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 
€. 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. 
Norr.—Mr. Murchison in his magnificent work styled the Silurian System, has 
jmepenei the name of calymene Downingie for one of Professor Brongniart’s fos- 
sils, called C. Macrophthalma, and restricts the term Macrophthalma to the one 
which I have named Calymene Bufo. There are several objections to this no- 
menclature. Ist, The C. Macrophthalma, Brong. was long ago divided into two 
Species by me for the reason above stated. 2d, In M. Achille Comptes large pic- 
torial illustrations of the Regne Animal, the vs ’ Macrophthelma is represented by 
Brongniart's figure 4, A. B.; naturalists therefore already know it under that name. 
The following are Mr. Murchisott $ 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 
sane plate, judging from the ovate, accuminate head and the tubercles on the fore- 
ad is our C. Downingie. 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 Toctin 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 
