8o 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Hydrozoa. — No appearance ; none occur before the Arenig rocks 

 were deposited. 



Actinozoa. — ISTo traces of Ccelenterata in any form. 



Echinodermata. — None occur in the Lingula-flags. The cystidean 

 Protocystites menevensis is Menevian only ; and the first Crinoid 

 appears in the Lower Tremadoc of Ramsey Island. 



Annelida. — Three genera and three species. The characteristic 

 Gruziana semiplicata, Salt., hitherto has only been found in the Cam- 

 brian grits of the Bangor area, near Cwm Grainog and Carnedd- 

 ffiliast, in North Wales (Lower Lingula-flags of the Survey). 



Specimens of this Gruziana or an allied species have occurred 

 below the Stiper stones in the Shelve country, W. of the Longmynds. 



Scolicoderma tubercidata, from Pentre-felen quarry, near Wem 

 Gate, Caernarvonshire, and Helmintliit.es from the Maentwrog sand- 

 stones. None of these forms occurs out of the Lower Lingula-flags. 



Crustacea. — This class is nearly equal in zoological value to what 

 it is in the Menevian. 9 genera and 25 species have been described : 

 14 of the same species appeared before in the Menevian, and therefore 

 occur in both formations ; 6 species {Agnostus princeps, A. trisectus, 

 Anopolenus Salteri, Microdiscus punctatus, Paradoxides aurora, and 

 P. Hicksii) pass to the Upper Lingula-flags. Like the Menevian 

 beds it is the home of Agnostus, 6 species of that genus occurring ; 

 but only 2 are peculiar or confined to the Lower Lingula-flags, 

 viz. Agnostus limbatus and A. nodosus ; besides these Olenus cata- 

 ractes, Salt., 0. micrurus, 0. gibbosus, and 0. truncatus ? are also 

 Trilobites confined to this horizon ; the Phyllopod Hymenocaris 

 vermicauda essentially characterizes the Lower Lingula-flags ; so 

 that, large as the Crustacean fauna appears (25 species), there are 

 only 8 that are really Lower-Lingula species ; the remaining 17 

 ally the Lower Lingula either with the two formations below or 

 with the Upper Lingula and Tremadoc above. The 7 typical spe- 

 cies are given above. The genus Gonocoryphe, which is very largely 

 represented in the Lower Cambrian rocks (by no less than 21 spe- 

 cies), has no distinctive or peculiar form in the Lower Lingula-flags ; 

 4 occur, but none are restricted. They are Gonocoryphe applanata, 

 G. bucephala, G. humerosa, and G. variolaris. 9 species of the 

 genus Gonocoryphe occur in the Upper Lingula-flags ; and, as we 

 shall see, this division possesses also more peculiar forms and a 

 larger specific Crustacean fauna than the Lower Lingula-flags, but 

 fewer genera. The species of Gonocoryphe and other genera are as 

 follows — Agnostus obtusus, A. princeps, A. trisectus, A. Turneri, 

 A. venulosus, Ampyx pramuntius, Anopolenus Salteri, Gonocoryphe 

 abdita, G. bufo, G. depressa, G. invita, G. malvernensis, G. longispina, 

 G. Plantii, G. simplex, G. Williamsoni, Microdiscus punctatus, Olenus 

 bisulcatus, 0. jlagellifer, 0. {Splmrophthalmus) humilis, 0. obesus, 

 0. pauper, 0. pecten, 0. (Peltura) scarabceoides, 0. serratus, 0. spi- 

 nulosis, Paradoxides aurora, and P. Hicksii, also Primitia sol- 

 vensis. 



Bryozoa. — None have yet appeared. 



