ON THE FOSSIL PHTLLOPODA OF THE PALAEOZOIC ROCKS. 299 



and has five plates of twenty-eight species in seven genera (including 

 some of both the bivalve and the univalve Phyllocarida) . 



The genera here treated of are Hymenocaris, Lingidocaris, Saccocaris, 

 Caryocaris, Apfychopsis, Peltocaris, Pimiocaris, and Discinocaris. 



I. Of Hymenocaris we know of only two species, both British, namely, 



(1) H. vermicauda, Salter, very common in some beds of the Lingula- 

 flags in North Wales ; and (2) H. lata, Salter, represented by a unique 

 and distorted specimen from the same strata. 



II. Of L'ingulocaris there ai'e (1) L. lingulcecomes, Salter ; (2) L. sili- 

 quiformis, Jones ; and (3) L. Salter iana, T. R. J. and H. W. These are 

 from the Cambrian of North Wales. 



III. Saccocaris major, Salter, from the Lingula-flags, and S. minor, 

 T. R. J. and H. W., from the Arenig series, are described and figured. 



IV. Caryocaris Wrightii, Salter, and the thinner C. Marrii, Hicks, 

 from the Skiddaw slates of Westmoreland, are fully treated of; and it is 

 suggested that the latter form is possibly due to a sexual difference. 



V. Of Aptychopsis we have recognised thirteen species, mostly 

 British : I. A, prima, Barrande, with its varieties longa and secunda, all 

 Bohemian. 2. A. Barrandeana, sp. nov., and its variety Irevior, nov. 



3. A. cordiformis, sp. nov. 4. A. lata, sp. nov. 5. A. glabra, H. W. 

 6. A. Wilsoni, H. W. 7. A. Salteri, H, W. 8. A. LapwortU, H. W. 

 9. A. ovata, sp. nov. 10. A. suhquadrata, sp. nov. 11. A. angulata 

 (Baily). 12. A. ohlata, sp. nov. 



Nos. 5 and 8 are probably represented among the several figures of 

 various forms of ' Aptychopsis prima ' given by Barrande in his ' Syst. 

 Silur. Boliemp,' vol. i.. Supplement, 1872, plate xxxiii. 



Nos. 10 and 11 are fi'om the Silurian of Ireland; the others (excepting 

 No. 7, from South Wales) are from the Moffat series of South Scotland. 



VI. Three species of Peltocaris are (1) P. aptyclioidcs, Salter ; 



(2) P. anatina, Salter ; (3) P. patula, sp. nov. 



Like Aptychopsis, Peltocaris is an Upper-Silurian British form, with 

 some representatives in the Middle Silurian. 



VII. Pimiocaris Lapworthi, Etheridge, jun., a rare Silurian form, is 

 known in Ayrshire and Westmoreland. 



VIII. Of the round subconical tests, undivided except by the tri- 

 angular nuchal notch, Discinocaris gives four species, all from the 

 Upper or Middle Silurian of South Scotland and Westmoreland : 1. D. 

 Browniana, H. W. 2. J), avails, sp. nov. 3. D. undulata, sp. nov. 



4. D. gigas, H. W. 



The British specimens here referred to belong to — (1) the British 

 Museum ; (2) the Museum of Practical Geology and Geological Survey 

 of Great Britain ; (3) Museum of the Geological Survey of Scotland ; 

 (4) Museum of the Geological Survey of Ireland ; (5) Woodwardian 

 Museum, Cambridge ; (6) Museum of the Owens College, Manchester. 

 The authorities of these institutions have courteously given ns flicilities 

 (by loan or otherwise) for studying the specimens. For the loan of a 

 large series we owe thanks to Mr. D. J. Brown, of Moffat, and for others 

 to Dr. C. Lapworth, of Birmingham. The late Mr. James Dairon, of 

 Glasgow, also obligingly lent us some specimens. 



The PinacaridcB (Difhyrocaris, &c.) have next to be described and 

 figured in detail ; and further descriptions and figures are required of the 

 Ceratiocaridre, for which the Committee have accumulated much material. 

 Mr. J. G. Williams, F.G.S., of Ffestiniog, has lent the Committee a large 



