80 Dr. J. inck/ehorongh— 



VI. — LocoMOTORY Appendages of Trilobites.' 



By John Mickleborough, Ph.D. 



Principal, Normal School, Cincinnati, Ohio, U.S.A. 



THE discoveries and investigations of palaeontologists touching 

 the question of ambulatory and branchigerous appendages of 

 the Trilobites have been entirely ignored by many of the ablest 

 workers in the science. The important evidence which Mr. Billings 

 produced was unsatisfactory to both Dana and Verrill. In 1881, after 

 many years of untiring labour, Mr. C. D. Walcott (in the " Bulletin 

 of the Museum of Comparative Zoology at Cambridge College ") 

 furnished most conclusive proof of the existence of appendages to 

 the cephalic, thoracic, and abdominal divisions of Calymene, Ceraurus, 

 and Acidaspis. He says : " the discoveries have been received in 

 about the same manner " as those of Billings and others — with 

 incredulity, and as " having little value." 



To confirm the conclusions of these naturalists, who have aifirmed 

 the existence of Trilobite legs, and possibly shed some light on the 

 character of the ventral surface of these crustaceans, and thereby aid 

 in the determination of ichnological specimens, is the object of the 

 writer. The conclusions here reached are based upon the work of 

 predecessors, and the specimens of Asaphus megistos, which were 

 found by Mr. James Pugh (they now belong to Mr. David McCord), 

 two niiles north of Oxford, Ohio, in the upper portion of the Hudson 

 Eiver Group. 



Although Ch. Mortimer, as early as 1750, and Linnaaus, in 1753, 

 had determined the crustacean character of the Trilobites, at least, 

 in zoological affinities, thej'^ were placed with Limulus, yet more than 

 a century elapsed before any discovery of feet or antennee was made. 

 In 1864, Mr. Billings discovered the presence of legs in a specimen 

 of Asaphus platycephalus, from the Trenton Limestone of Canada. 



To show the distrust in the minds of naturalists, we quote from 

 the pamphlet of Mr. C. D. Walcott, page 196 : " The instances of 

 the discovery of the animal other than the dorsal shell and hj'postoma 

 are rare. M. Barrande, in reviewing the reported discoveries made 

 of the appendages of the Trilobites to the date of the publication 

 of his volume i. 1852, says : ' Unhappily, all the researches have 

 resulted in nothing more than the discovery of the pieces of the 

 mouth named hypostoma and epistoma, and the intestinal canal.' 

 Again, in his supplement to volume i., 1872, he says: 'The few 

 scattered observations of parts found which might belong to the 

 Trilobites have little value, and were accepted as such by naturalists.' " 



In 1872, Dr. A. S. Packard, in his work on the Development of 

 Limidus polyphemus, page 185, says: "Though disposed to regard 

 the processes figured by Mr. Billings as feet, still the proof is un- 

 satisfactory. The Trilobites probably had habits similar to those of 



^ From the Journal of the Cincinnati Society of Natural History, vol. \i. 1883. 



Since printing this Dr. Micklehorounh has most obligingly announced that he has 

 despatched cliches of his illustrations, which we hope to give in our next Number. — 

 Edit. Geol. Mag. 



