C. E. Beecher — Restoration of Stylonurus Lacoanus. 145 



Art. XV. — Restoration 'of Stylonurus Lacoanus, a Giant 

 Arthropod from the Upper Devonian of the United States / 

 by Charles E. Beecher. (With Plate I.) 



Lsr the animal kingdom, the attribute of bigness has come to 

 be regarded as one of the prerogatives of the vertebrates. On 

 this account, invertebrates seldom receive credit for having a 

 size of more than a fraction of a cubit, and are looked upon as 

 objects to be held in the hand or viewed under a lens. As a 

 matter of common experience, and probably also of congratu- 

 lation, large invertebrates are rare, and some whole classes can- 

 not furnish a single individual measuring more than a few 

 inches in greatest diameter. 



In a list of arthropod giants, the subject of the present note 

 must be included, and will take equal rank with the Giant 

 Spider-Crab of Japan (Macrocheira Kaempferi) and the great 

 " Seraphim " of the Scotch quarrymen {Pterygotus anglicus). 

 The former can safely claim to be the largest representative of 

 the Brachyurans that has ever existed, and to the 'latter may 

 be accorded the same distinction among the Merostomes. 



The living species of the Merostomata comprise only the 

 American and Moluccan Horse-Shoe Crabs, Limulus poly- 

 phemus and L. moluccanus. The latter sometimes attains a 

 length of three feet, and measures eighteen inches across the 

 carapace. To find other species in this order worthy of com- 

 parison with the huge Brachyuran of Japan, it is necessary 

 to go back to the Paleozoic forms, and among these the larger 

 species of Pterygotus, and the Stylonurus here noticed, fill all 

 the requirements. It should be borne in mind, however, that 

 these statements are based upon comparative lengths and 

 breadths. If bulk alone were considered, the common lobster 

 (Homarus americanus and H. vulgaris) should be mentioned, 

 though in length and extent of limbs it would be considerably 

 smaller. 



Concerning the size of the Scotch " Seraphim," Dr. Henry 

 Woodward 10 states that " From our present knowledge of the 

 almost perfect remains of Pterygotus anglicus, and on the 

 evidence of the numerous detached portions of this extinct 

 genus, we are justified in concluding that it attained a length 

 of six feet, and a breadth of nearly two feet at the widest part 

 of its body." This huge Merostome has been found in the 

 Lower Old Ped Sandstone of Scotland, at a horizon nearly 

 equivalent to the one furnishing the remains of Stylonurus in 

 America. Thus what seem to be the two largest species of 

 this class were contemporaries, though not associates. 



