THE CRUSTACEA OF THE SILURIAN ROCKS OF 

 SOUTHWEST SCOTLAND. 



BY B. N. PEACH, F.R.S. 



PHYLLOCAEIDA. 



THE phyllocarids are represented by Caryocaris Wrighti in the Arenig 

 rocks of Balcreuchan Port and Bennane Head near Ballantrae, and of 

 Ravensgill near Abington, the form being also found elsewhere in rocks of this 

 horizon. The Caradoc rocks of Girvan have yielded two genera and species, 

 viz. Pinnof-aris Lapworthi, which occurs in the Balclatchie sandstones at their 

 base, and Solenocaris solenoides in the Drummuck and Threave beds near their 

 upper limit. In the Tarannon rocks of Blackwood Head, near Dailly, 

 Discinocaris gigas has been found. This form occurs at Moffat in the Birkhill 

 shales at a somewhat lower horizon along with D. browniana and Peltocaris 

 aptychoides. These two latter forms have been recorded from the Birkhill 

 shales, outcrops between Portpatrick and the Mull of Galloway, and reappear 

 along with these shales in Ireland on the opposite shore of the Channel at 

 Coalpit Bay, near Donaghadee. A form doubtfully referred to Peltocaris 

 has been recorded by Mrs. Gray from Penkill in the Girvan area. 



The genus Aptychopsis has not yet been recorded from the Girvan area, 

 nor from the Wenlock rocks of the northwest margin of the southern 

 uplands, but two species have been recorded from the Tarannon and 

 Wenlock rocks of Burrow Head to the south of Wigtown. All the forms 

 above enumerated seem to have associated with graptolites, as they are 

 mostly found embedded in graptolite-shales, and seem like the graptolites to 

 have flourished best at or near the limit of sedimentation. 



The genus Ceratiocaris is the prevailing phyllocarid form in the Wenlock- 

 Ludlow rocks of Lesmahagow and the Hagshaw Hills, no fewer than nine 

 species having been recorded from these beds. They occur in such numbers 

 in certain bands that they have given the name to a very important 

 sub-zone of the Ludlow rocks of the Lesmahagow inlier, viz. that from which 

 the Ludlow fish- and scorpion-remains have been obtained. It is from these 

 beds that the specimen showing abdominal appendages described by R. 

 Etheridge, Jnr., 1 and a considerable amount of the material which is 

 figured by Jones and Woodward in their monograph 2 was obtained. 



The species of this genus seem to have frequented the muddy bottoms 

 where slow deposition was going on, for their remains are most numerous in 

 certain finely-laminated calcareous beds which are comparatively free 

 from the remains of lamellibranchs and gasteropods which crowd many 

 of the less finely -laminated beds of the Lesmahagow inlier. In the 



1 Memoirs Geol Surv. Scot. " Explanation " of Sheet 23, p. 93. 



2 Palaeont. Soc. Monograph on "British Palaeozoic Phyllocarida," part i. 



