Packard.] ^"^ [Feb. 5, 



Discovery of the Thoracic Feet in a Carboniferous Phyllocaridan. By A. S. 



Packard. 



{Bead before the American Philosophical Society, February 5th, 1S86.) 



It is a matter of some surprise that notwithstanding the large number 

 of fossil Phyllocarida from the Palaeozoic strata made known to us by the 

 researches of McCoy, Salter, Barrande, H. Woodward, James Hall, J. M. 

 Clark, Pi. P. Whitfield, C. E. Beecher and others, no definite, unmistaka- 

 ble traces of the limbs have been discovered. So far as we are aware, no 

 portions of the antennae of either pair, nor of the thoracic or abdominal 

 limbs (except those next to the telson), have been figured or described, 

 though many specimens of the fossils have been subjected to the scrutiny 

 of our leading paleontologists. While most of the species are represented 

 by the bivalvular carapace alone, which must have been, as in the recent 

 Nebalia, easily detached after death from the body so as to float away by 

 itself, still in some cases, as in that of C'eraliocaris stygia Salter, figured by 

 Messrs. Jones and Woodward in the Geological Magazine for September, 

 18S5, the abdominal segments, with the hist pair of uropoda and the telson, 

 are distinctly preserved, while in other cases the large toothed mandibles 

 are preserved in place between the valves of the carapace ; the rostrum 

 has also sometimes been preserved. But we should have expected ere this 

 to have become acquainted with the nature of the antennae and the ante- 

 rior abdominal appendages, if, as we have good reason to suppose, they 

 were like those of the modern Nebalia. 



In their diagnosis of the genus Ceratiocaris, Messrs. Jones and Wood- 

 ward in referring to the body, state : "Body many jointed, with fourteen 

 or more segments, of which 4-7 extend beyond the carapace ; ornamented 

 with delicate raised lines. Some or all of these segments bore small, 

 lamelliform, branchial appendages."* 



Although Messrs. Jones and Woodward have kindly sent me nearly all 

 their valuable papers on fossil Crustacea, tiiose cited in the foot- note, un- 

 fortunately are not among the number, and hence I am unable to refer to ' 

 them. Mr. Etheridge's note in the Annals and Magazine Natural History 

 is as follows : 



"At the Brighton meeting of the British Association, Mr. II. Wood- 

 ward, F.R.S., noticed the discover}' of the 'swimming gills' of Ceratio- 

 caris, to which Iliad previously drawn his attention. On a slab of thin 

 flaggy shale from the Upper Silurian series of Lesmahagow are exposed, 

 the caudal segments, telson, and caudal appendages of a Ceratiocaris. 

 From the ventral margin of the terminal segment proceeds abroad paddle- 

 shaped membraneous (?) expansion, presenting a strong marginal outline, 



♦See the Sixth Report on Fossil Crustacea, Brit. Assoc. Report for 1872, p. 323, 

 and Geological Magazine, ix, p. 564. Also a descriptive note by Mr. R. Etherldge, 

 given in the Mem. Geol. Surv. Seotl. Explan. Sheet 23, 1873, p. 93, and Annals 

 and Mag. Nat. Hist. Ser. 4, Vol. xiv. I87J, p. 9. 



