CRUSTACEA. 133 



the reniform eyes', the absence of occipital lobes, the great length of the pygi- 

 dium and the number of its annulatioris are all Phillipsioid characters. 



The species may ultimately prove to be a Carboniferous fossil, hut any satis- 

 factory determination of its age must await the acquisition of more complete 

 material. 



Proetus Missouri ensis. 



PLATE XXIII, PIG 32. 



I Missowriensis, Shumard. Geol. Rept. Missouri, p. 196, pi. B, fig. 13. 1855. 

 Proetus auriculatus. Hall. Descr. New Species of Fossils, etc., p. 79 1861. 

 Proetus auriculatus, Hall. Fifteenth Rept, N. V. State Cab. Nat. Hist., p. 107. 1862 

 Phillipsia Shumardi, Herrick. Bull. Sci. Lab. Denison Univ., vol. ii. pt. 1, pp. 58, 69, pi. vii, fig. 1 I. 1887. 



This species is noticed here in order to call attention to its correct determina- 

 tion and its proper synonymy. The original of Mr. Shumard's Proetus Missouri- 

 ensis, described from the Lithographic limestone of Missouri, formerly regarded 

 as of Upper Devonian age, is apparently identical with the detached cephala 

 and pygidia from the Waverly sandstones of Licking county, Ohio, which were 

 described in 18G1 under the name Proitus auriculatus, Hall. Recently an en- 

 tire individual of the species from Licking county, Ohio, has been described 

 by Herrick (he. tit.), under the term Phillipsia Shumardi. The change of name 

 proposed by this author arises from the consideration that if the fossil belongs 

 to the genus Phillipsia, the designation Phillipsia Missouriensis would be inad- 

 missible as this name had been used by Shumard for a species from the coal 

 measures at Lexington, Missouri, described in 1858, (Transactions St. Louis 

 Academy of Science). Without entering into a discussion upon the right of 

 priority under these circumstances to the specific term Missouriensis, the 

 evidence, afforded by the entire specimen of the species, points distinctly to the 

 fact that the genus to which it belongs is Proitus and not Phillipsia. The form 

 of the glabella is in some respects similar to that of certain species of Phillipsia, 

 being somewhat expanded anteriorly, the fourth lateral furrows strong and 

 reaching to the occipital furrow, the third and second short and the first 

 obsolete. Such variations frequently occur within the limits of the genus 

 Proitus (P. canaliculatus, P. granulatus, P. crassimarginatus). The occipital lobes, 



