648 PEOCEEBIKGS OF THE GEOLOGICAL SOCIETY. 



typical southern area. I must, however, state that no group in the 

 whole Devonian series is so difficult of identification, or perhaps 

 more erroneously determined ; the Crinoidea and Asteroidea, in nine 

 cases out of ten, occur only as casts and moulds ; yet some of the 

 Upper Devonian beds of Baggy, Marwood, Croyde, Braunton, &c. 

 are literally composed of the rusty decomposed remains of the 

 Echinodermata, especially the Crinoidea. The 20 known species in 

 the whole Devonian rocks are irregularly distributed through them ; 

 though 8 certainly occur in the Middle South Devonian beds. A.n- 

 nelida : only one determined species occurs, Tentaculites annula- 

 tus^, known in both North and South Devon. Crustacea : 5 genera 

 and 13 species occur in the Middle series in South Devon, one of which 

 only, Trimerocephalus Icevis, is known in the Ilfracombe series of 

 ITorth Devon, and was found by Mr. Yalpy in the gritty shales of 

 Watermouth near Ilfracombe ; this is important as being another 

 and important link in evidence of the same species of Crustacea 

 occurring in the two areas. Mr. Jukes states that he found PJia- 

 eops latifrons in the Lower Devonian slates of Lynton (Valley of 

 E,ocks) ; and on his or Mr. Baily's authority I insert it in my list ; 

 these two species of the family Phacopidse give us some hope that 

 Homdlonotus and Harpes will ere long reward the labours of some 

 patient geologist. Polyzoa : 6 genera, and 8 species out of the 12 

 known, occur in South Devon ; we cannot, however, at all depend 

 upon the specific characters of these generally badly preserved and 

 minute organisms; and as such they possess little or no stratigraphical 

 value. Fenestella antiqua is, according to every one, in everything, 

 from the slates of Looe to the Coomhola grits &e. Prof. Phillips 

 admits 4 varieties of this species, all having different geographical 

 positions; each should be carefully examined and understood, if 

 weight is to be attached to so ubiquitous a deep-sea form. Lons- 

 dale even refers it to the Silurian rocks ; the whole group of the 

 palseozoic Polyzoa requires great and critical examination. 



BracTiiopoda. — This class, hke the Actinozoa among the Coelen- 

 terata, highly typify and characterize the Middle Devonian rocks of 

 South and I^orth Devon ; 23 genera and 68 species have been 

 accurately determined as coming from these beds in South Devon ; 

 10 genera and 22 of these species are common to the slates and 

 limestones of the middle group in North Devon ; and by compari- 

 son with those of the Ehine, Belgium, and France, in beds of the 

 same age, no less than 47 species are common to the two marine 

 areas ; 7 only of these, viz. — 



Ehynchonella acuminata, Martin. Spiriferina cristata, Schloth. 



pleurodon, Fhill. 



pugnus, Martin. 



reniformis, Sow. 



pass up to the Lower Carboniferous, all of which, with the excep- 

 tion of JRhyncTioneUa acuminata, form an important feature in the 

 Upper Devonian slates and limestones of Baggy, Marwood, Sloly, 



*■ There are perhaps two if not three species, though their remains are 

 obscure. 



Streptorhynchus crenistria, FMll. 

 Strophomena rhomboidalis, Wahl. 



