ON THE FOSSIL rnYLLOPGDA OF THE I'AL.BOZOIC KOCKS. 



89 



typical, and know them as Apti/chopsis prima, about 2.5 ram. lonpr by 

 20 mm. in width ; and with the nuchal suture at an anpflo of 50°. Two 

 specimens in the liritish Museum (Natural History) in limestone from 

 Butowitz, and labelled * Apti/chus ? 2)nmus,' belong to this form; also figs. 

 0-11 and 19 in pi. oli of the ' Sil. Syst. Bohome,' &c.; and two small 

 round individuals labelled ^ AptycJnis ? seciindus' (15 mm, in each 

 diameter ; nuchal suture with slope of 40°), in shaley mudstone from 

 Borck, belong to the varietal form, Aplijchopsls prima, Barrande, var. 

 secunda. 



M. Barrande included with doubt another form in this genus — namely, 

 his ApUjcliopsis ? ivjlafa, 'Syst. Sil. Bohem.' vol. i. Suppl, p. 459, pi. 33. 

 figs. 22, 23. But this seems to be an Entomis, and may stand as Enlomis? 

 inflata (Barrande), from the hills between Lodenitz and Bubowitz, 

 Etage Ee 2. 



There are no Goniatitcs in ' I5tage E,' representing the lower part of 

 the ' Fauna III.,' which is equivalent to the Upper Silurian. There are, 

 however, some Goniatitcs (five species), rather higher up, in ' Etage P,* 

 which is in the middle part of ' Fauna III.' 



M. Barrande's careful and elaborate account of what was known of 

 Aptijchopsis up to 1872 is almost sufficient in every respect. See tho 

 ' Syst. Sil. Boheme,' vol. i. Suppl. 1872, p. 455. 



In the Sixth Report on Fossil Crustacea to the British Association 

 for the Advancement of Science, in 1872, Dr. Henry Woodwai'd defined 

 some Phyllopodous species and grouped them under the same name (inde- 

 pendently arrived at) as M. Barrande proposed in the same year (see 

 above). See also Dr. H. Woodward's note on Peltocnris, Disclnocaris, and 

 Aptijchopsis in Nicholson and Ethcridge's 'Fossils of the Girvan District,' 

 1880, pp. 210, 211. 



"M. Barrande (np. cif. p. 455) states that Aptychopsis had been found 

 by Professor Angelin in Dalecai'lia and Gothland in Upper Silurian strata 

 at about the same horizon as that in which they occur in Bohemia. We 

 cannot, however, learn of tho existence of any Scandinavian specimens. 



2. Aptijchopsis Wilsoni, IT. Woodward, 1872. ' Sixth Report on Fossil 

 Crustacea — Report British Association for 1872, 1873,' p. 323 ; 

 ' Geol. Mag.' vol. ix. 1872, p. 565. 



This species has a discoidal shield, and was briefly described, in 1872, 

 as having a straight (not circular) nuchal suture (making a triangular 

 cephalic plate) and a well-marked median or dorsal suture, and as mea- 

 suring l.\ inch in length, by IjJ inch across. There are three specimens 

 of Aptychopsis Wilscni in the British Museum, and they would probably 

 be almost round in outline if quite perfect. Thoy arc from the Riccarton 

 beds (Upper Silurian), at Sliankend, Slitrig Water, near Hawick; Gad's 

 Linn, near Hawick ; and ElliottsGeld, near Hawick, Dumfriesshire. 



We may add that tho cephalic notch is not so deep as in some allied 

 forms; its iipex was about one-third of the length of tho median suture 

 from the front edge of the shield. The usual concentric lines are apparent 

 on some specimens. 



One largo specimen would measure 40 mm. in each diameter if com- 

 plete ; its nuchal suture slopes 40°. Another specimen (imperfect) 

 measures 30 mm. across, and has a nuchal slope of G0°; difference of 

 pressure has caused this discrepancy. 



