ON THE FOSSilL rilYI.LOrODA OF Till; TALKO/OIC liOCK.S. 



9o 



Soc.» 



"Whcro llio front ('(lijes aro cllipticaliy ronndi'd, thoro wonld ho a 

 nlipfht notch in tho saiiio poHitioii as that in Ai>hjcli(ipsis; but thorn is no 

 «!vitlenco of any cephalic or rostral pieco having occupied it. On tho 

 contrary, tho genus may have been truly bivalve, like Httflicria and other 

 such l*hyllopods. This genus is known in tho Lower and I fppor Silurian. 



1. Pinnocnris Lnjurnrfhi, R. Ethoridge, Jun. ' Proc. R. Phys. Soc. 

 Edinb.' vol. iv. (1878), p. lt;i», pi. 2, tigs. 3-5; ' Fo.s8ils of Girvan,' 

 Ac.' p. 280, pi. l.J,, tigs. 17-21). 



Figs. 18, 10, and 20 have ihe postero- ventral edge of tho valve much 

 more contracted than fi<r. 17 (imperfect) would have if completed accord- 

 ing to tho contours of its remaining linos of growtli. Possibly a varietij 

 is here indicated. Moreover, tlie front edge of tig. 17 is much more 

 rounded (more semicircular) tlian tlio others, mlrnittiug of little or no 

 cephalic piece. These aro from the Lower Silurian at IJaleletchie, 

 riirvan, Ayrshire. A specimen of tin; form orviiriety sliown by fig. 17 — 

 that is, witli the hinder portion less piiiclied in— i« i" the Uritish Museum, 

 from tho Upper Silurian of Kt-ndal. 



The shield is triangular -obovate, if tho two lateral pieces bo laid out 



No Cioniatites accompany these specimens. 



CaUDAI, Al'l'KNDAGES. 



From the analogy of allied forms, we should expect that these 

 Apudiform Crustacesins had more or less extended abdominal segments 

 and caudal spines. With reganl to this part of their organism wo have 

 not much to remark, except that a few such styles or stylets as aro 

 attached to th(> telson in known forms liav(( been found in strata containing 

 Discinoi'uris, Pultvcavh, or Ajihirhiipxi,<. Thus, at the Skelgill Beck, 

 Ambleside, in tho Coniston (U|)per Silurian) mndstones, in which 

 Disi-lnocaris and Feliocaris occur, Mr. J. 10. Marr found a small tapering 

 caudal spine, 15 mm. long, and delicately striate (now in tho Cambridge 

 ^[u.seum). This may have belonged to one of tho forms just mentioned. 

 So, also, there is a small thin spine, '.\h mm. long, and apparently dotted 

 with tho bases of minute prickles, in tho British Museum, from the 

 Riccarton (Upper Silurian) beds of Shankend, near Hawick ; and two 

 (probably the remnant of a .set of three), one o") mm long and fluted, 

 and the other 20 mm. long, from the Buckholm beds (Upper Silurian) of 

 the Gala group, Meigle Hills, Galashiels. These are large enough for 

 Ceraliocariii, but only AptijcJiopsis apd I'ellucariti are known in these 

 strata. 



We may add that a few small caudal spines, 20 ram. long, have been 

 found by Mr. Marr in tho Upper Arenig Slates at tho Nantllo tramway, 

 Pont Seiont, near Caernarvon. Here they aro associated with Giryocaris. 

 See ' First Report on tho Palaeozoic Phyllopoda.' 



