THE FAUNA OF THE ST. JOHN GEOUP. 117 



* 

 have cited, A. Barrandei presents the greatest size (taillé) known at the present time in the 

 whole tribe of trilobites. It was found in the neighbourhood of Neffiez, in the Department 

 of l'Hérault, in France. We hope that our illustrious teacher and friend Mr. de Verneuil, 

 possessor of this scientific rarity and so many others, will publish some day the descrip- 

 tion and the form. Only one example has presented the length indicated ; hwï several 

 others of smaller dimensions have been found." 



From these remarks it may be inferred that at the date cited, this species had not been 

 figured or described. 



1882. — Ten year after the publication of Barrande's work describing the great Asaphus 

 above mentioned, Scandinavia, already known as having produced very large species, 

 both of the First and the Second Fauna, was found to have another very large trilobite. 

 Prof. "W. C. Brogger ' met with a very large tail-piece of a Megalaspis (M. acuticauda, Aug.) 

 which appeared to indicate a species of even greater length than the great French Asaphus 

 of de Verneuil. Mr. Brogger did not find the whole test of the animal, and therefore, his 

 estimate of the length is based on the known proportions of the parts in smaller indivi- 

 duals ; from these he estimates that the length of this great trilobite must have been 403 

 mm. or nearly 16 inches. 



From the above remarks it may be seen that three of the great Asaphi of the Second 

 Fauna exceed in length any of the Paradoxides known ; but in estimating their size, their 

 breadth and general form is to be taken into account. The form and description of Angelin's 

 two great species of Scandinavia are well known. In 3Ieg(daspis acuticauda, according to 

 Brogger's figures and descriptions, the narrow form was three times longer than broad, 

 and the broad form two and half times longer than broad ; both were drawn out and 

 sharply pointed at each end. The length of Megalaspis herns, another Scandinavian species, 

 was less exaggerated ; its length as figured by Angelin was about 13J inches, and its 

 extreme width about *7^ inches, or nearly twice as long as broad ; this species, also, was 

 pointed at each end. 



No true Asaphus, except the American relatives of A. platycephalus, approaches the 

 dimensions of these great Scandinavian trilobites, so I am led to surmise that the French 

 species named by de Verneuil, and not described, may be a Megalaspis, and thus, notwith- 

 standing its great length, of no greater size than Megalaspis acuticauda. 



Very different was the form of the great American Paradoxides ; for Mr. Salter informs 

 us that P. Bennellii was " as wide as long." P. Harlani was more slender, but, as will be 

 seen in the sequel, Ihe Acadian species I am about to describe, fully makes up in breadth 

 what may be lacking in length to place it on a par with any species hitherto described, 

 except the American representatives of Asaphus plali/cephalus. 



The succeeding tables upon the following pages exhibit the relative sizes respectively 

 of the great trilobites of the several types, which have successively held sway in geolo- 

 gical time. The data for the European species are taken mostly from Barrande's " Système 

 Silurien de la Bohême," supplemented by notes from Angelin's " Palœoutologica Scande- 

 navica ", and Brôgger's " Silurischen Etagen 2 und 3." 



' Die Silurisclien Etagen 2 und 3, pp. 83-85. 



