292 Reports and Proceedings. 



corresponding witli the eight segments of the thorax, to the under- 

 side of which they had been attached. The appendages take their 

 rise close to the central axis of each segment, and all curve for- 

 wards, and are thus most probably ambulatory rather than natatory 

 feet. They appear to have had four or five articulations in each 

 leg. 



Three small ovate tubercles on the pygidium may perhaps indi- 

 cate the processes by which the respiratory feet were attached. 



Mr. Billings referred to the large number of Trilobites which have 

 been examined, and expressed his belief that only the most perfectly 

 preserved specimens are likely to have the organs on the underside 

 preserved. 



(2) Mr. Billings next described the doublure or pleura in the Tri- 

 lobites, comparing it to that of Limulus. He then proceeded to describe 

 a row of small scars and tubercles on the underside of the pleuraB, 

 to which both Dr. Volborth and Dr. Eichwald believed soft swim- 

 ming feet or hard horny legs had been attached. As these were 

 first seen by Dr. Pander in a Eussian Trilobite, Mr. Billings has 

 called them " Panderian organs." He thinks soft natatory appen- 

 dages may have been attached to these scars. 



(3) Mr. Billings directed attention to the Protichiites and Cli- 

 mactichnites, which he thmks may now be safely considered to be 

 the markings left by Crustacea, belonging to the division Trilohita. 



(4) Finally, Mr. Billings described a section of a rolled- up Caly- 

 mene senaria, the interior cavity of which appears to be full of 

 minute ovate bodies, from l-80th to 1-lOOth of an inch in diameter. 

 These small ovate bodies the author believes to be eggs. 



2. " Note on the palpus and other appendages of Asaphis, from 

 the Trenton Limestone, in the British Museum." By Henry Wood- 

 ward, Esq., F.G.S., F.Z.S. 



Mr. Woodward, when comparing the Trilobite sent over by Mr. 

 Billings with specimens in the British Museum, presented by Dr. J. 

 J. Bigsby, F.E.S., discovered, upon the eroded upper surface of one 

 of these, not only the hypostome exposed to view, but also three 

 pairs of appendages, and what he believes to be the palpus of one of 

 the maxillae. This furnishes an additional fact to Mr. Billings's most 

 interesting discovery, besides confirming its correctness. 



Mr. Woodward considers the so-called " Panderian organs " to be 

 only the fulcral points upon which the pleura move, and showed 

 that such structures exist in most recent Crustacea. 



He considered that the evidence tended to place the Trilobita near 

 to, if not in, the Isopoda Normalia. 



He remarked that the prominence of the hypostome reminded one 

 strongly of that organ in Apus, and suggested that we might fairly 

 expect to find that the Trilobita represented a more generalized type 

 of structure than their representatives at the present day, the modem 

 Isopoda. 



Discussion. — Mr. Woodward had carefully examined Mr. Billings's specimen, and 

 agreed with him in considering that there was undoubted evidence of the presence 

 of walking-appendageB under the thorax. The presence of such limbs might d 



