90 REPOBT 1884. 



3. Aptychopsis LapwortJd, H. Woodward, 1872. ' Sixth Report on 

 Fossil Crustacea,' in 'Report Brit. Assoc, for 1872, 1873,' p. 323; 

 ' Geol. Mag.' vol ix. 1872, p. 565 ; ' Quart. Jour. Geol. Soc.' vol. 

 xxxiv. 1878, p. 331. 



This Pbyllopod shield was also briefly described by Dr. H. Woodward 

 at the same time and in the same Report with the foregoing. It is oval, 

 8 lines long by 7 broad (1 line = -jVinch). It is concentrically striate in 

 most of the examples preserved, and in one case it retains the cephalic 

 plate. The best specimen has this plate in place, but the several parts 

 and the edges of the notch have been slightly damaged and disturbed by 

 pressure, so that its angularity is somewhat modified. This is from the 

 Birkhill Shales in Eldinhope Burn on the Yarrow, Selkirkshire. This 

 division of the upper part of the Moffat Shales ' is regarded as equivalent 

 to the lower part of the Middle Silurian (Lower Llandovery). Another 

 specimen in the British Museum is from the Birkhill Shales at Sund- 

 liope Burn, in the same neighbourhood, and another from the Grieston 

 Shales of the Gala Group, at Inverleithen, above the Moffat Group, and 

 equivalent to the upper part of the Middle Silurian. A good specimen 

 measures 17 mm. long by 14 mm. broad. Another appears to have been 

 23 mm. long by 18 mm. wide. The angle of the nuchal suture may have 

 been about 50°. 



A specimen of Aptycliopsis very similar to, if not identical with, 

 Aptychopsis Lapworihi, is in the University Museum, Cambridge, from 

 the Lower- Wenlock beds of Rebecca Hill, Ulverstone. It is labelled 

 ' Peltocaris anatina, Salter,' and is referred to under that name in the 

 'Catal. Cambridge Fossils, &c.,' 1873, p. 93. The frontal notch is 

 angular, the median sutural line is raised along the depressed shield, and 

 concentric stria? are present. 



In another specimen in the same Museum, the test has been narrowed 

 by lateral pressure, acting obliquely across the long axis of the shield, as 

 is indicated by imperfect cleavage-planes crossing the modified test at 

 an angle of about 60°. The frontal notch has been narrowed, its sides 

 made unequal, and its apex somewhat rounded. 



This specimen is from Skelgill Beck ; collected by Mr. Marr, F.G.S. 



What seems to be a similar example or a modified Aptychopsis, 

 squeezed into an even narrower and more lanceolate shape, has been 

 figured by Mr. James Dairon in the ' Transactions of the Geological 

 Society of Glasgow,' vol. vii. pi. 7, fig. 35, and referred to in the 

 Explanation of the plate as ' Discinocaris Broivniana, var. ovalis, Dairon.' 



All the little Phyllopod tests figured in this plate 7 are termed 

 ' Discinocaris Broivniana ' by Mr. Dairon ; but they appear to belong to 

 other genera. Fig. 29 looks like Peltocaris aptychoides. Figs. 31 and 

 34 are round shields of probably A. glabra, H.W. Fig. 35 seems to be 

 a specimen of either A. Lapivorthi or A. glabra much narrowed by 

 pressure ; but it may be otherwise. Figure 32 is a discoidal Aptychopsis, 



1 The classification of the successive formations in the Moffat district and vicinity 

 has been worked out by Frofessor Lapworth, see Geol. Mag. vol. ix. 1874, pp. 533-530 ; 

 Quart. Jour. Geol. Soc. vol. xxxiv. 1878, pp. 240-34G ; aud Proceed. Belfast Xat. 

 Field-Club, ser. 2, vol. i. part 4, Appendix IV. 1878; also Catal. Western- Scottish 

 Fossils, by Armstrong, Young-, and Robertson, 1876, p. 24. Although numerous 

 Phyllopod shields have been met with, no Goniatites have been recorded from these 

 beds. 



