384 Geological Society : — Dr. J. W. Dawson on the Structure 



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 

 pleurae, to which both Dr. Yolborth and Dr. Eichwald believed soft 

 swimming 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 

 appendages may have been attached to these scars. 



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

 macticlinites, which he thinks may now be referred to Crustacea, 

 belonging to the division Trilobita. 



(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 -^ to yj-^ of an inch in diameter. These 

 small ovate bodies the author believes to be eggs. 



2. " Note on the palpus and other appendages of Asajphus, 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.B-.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 pleurae 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 mo- 

 dern Isopoda. 



3. " On the Structure and Affinities of Sigillaria, Catamites, and 

 Calamodendron." By J. W. Dawson, LL.D., F.R.S., F.G.S., Prin- 

 cipal and Vice-Chancellor of M'Gill University, Montreal. 



The object of this paper was to illustrate the structure and affi- 

 nities of the genera above named, more especially with reference to 

 the author's previous papers on the " Structures in Coal " and the 

 " Conditions of Accumulation of Coal," and to furnish new facts and 

 conclusions as to the affinities of these plants. 



Wih reference to Sigillaria, a remarkably perfect specimen of the 



