66 REPORT — 1887. 



IV. Silurian Specimens Formerly Referreh to Dithyrocaris. 



1. [Dithyrocaris~\ aptyclioides, Salter, 1852 



= Peltocaris aftychoides, Salter, 1863. See the Second Report on the 



Palaeozoic Phyllopoda, 1884', p. 92. 

 Silurian . — Moffat, Scotland. 



2. [Dithyrocaris'] MurcMsoni, Geinitz, 1853. 



Geratiocaris Murchisoni (Agass.). See the Third Report on Palaeoz. 



Phyllop., p. 340. 

 Silurian. — Saxony. 



3. [Dithyrocaris ?] longicauda, D. Sharpe, 1853. 



D. ? longicauda, D. Sharpe, ' Q. J. G. S.,' vol. ix. p. 158, pi. 7, f. 3. 

 Geratiocaris ? longicauda, Jones and Woodward. Third Report on 



Palseoz. Phyllop. 1885, p. 354. 

 Silurian. — Near Bussaco, Portugal. 



4. [Dithyrocaris'] Jaschei, F. A. Roiiier, 1855. 



' Pateontographica,' vol. v. p. 8, t. 2, f. 13 ; and vol. xiii. 18GC, p. 219, 



referring to Romer's ' Beitrag 111. 17. 13 ' (misspelt ' Ditryocharis '). 



[Dithyrocaris] Jaschei, Romer. Kayscr, ' Abhandl. Geol. S])ecialkart6 



von Preussen und Thiiringischen Staaten,' vol. ii. Heft 4, 1878, p. 



7, t. 1, f. 13, 13a. 



Silurian. — Near Ilsenberg, Hartz. 



Referring to Romer's 'Beitrag III., p. 120, t. 17, f. 2,' and giving 

 more correct figures of the exterior and section. Doubtfully like a portion 

 of a bivalved carapace, filled with matrix and broken across. 



Kayser, Hid. p. 8, t. 1, f. 14, also describes and figures a dubious 

 fossil from the oldest Devonian rocks of the Hartz (the limestone of the 

 Upper Sprakelbach), which, Kayser says, looks like a tail-spine of a 

 Geratiocaris ; such, for instance, we may add, as G. jierornata, Salter ; see 

 our Third Report, p. 352. It may, however, have belonged to a Placoid 

 fish, as Kayser observes. A fragment of what may have been the 

 valve of a Nothozoe (ibid. p. 9, t. 1, f. 15) was found in the same lime- 

 stone. 



§ IV. Leaia. — Since the genns Leaia (mentioned in our First Report, 

 1883, p. 217) was established in the ' Monograph of Fossil Estherite,' 

 Pal. Soc, 1862, Appendix, p. 116, some other forms besides L. Leidyi 

 have been recorded ; and several additional localities have been noticed, 

 both for that species and L Williamsoniana and L. Salteriana, described 

 originally as varieties. The original rlescription of the genus and of 

 Leaia Leidyi (Lea) has been reproduced in Dr. A S. Packard's ' Mono- 

 graph of North- American Phyllopod Crustacea,' 1883, pp. 356-358. 



In 1870 the history and nature of the genus Leaia were fully treated of 

 by H. Laspeyres in the ' Zeitschr. deutsch. geol. Gesellsch.,' vol. xxii. pp. 

 773, &c., with definite descriptions and good figures of five forms as 

 specific types, distinguished by shape, proportions, and ornament — namely, 

 L. Leidyi, Lea, p. 743, t. 16, f. 3 Jj. 'Williamsoniana, Jones, p. 743 

 t. 16, f. 4; L. Baentschiana, Beyr. and Gein., p. 744, t. 16, f. 2 ; L. 'Wet- 

 iiaensis, Laspeyres, p. 745, t. 16, f 1 ; and L. Salteriana, Jones, p. 744, 

 t. 16, f. 5, the second, third, and fifth having previously been treated as 

 varieties by their describers. This paper is noticed in the 'Neues Jahrb.,' 

 1870, p. 922. 



