618 



G. H. VINE ON SILURIAN TJNISERIAL 



known species, and places it in a division by itself (C. Colony 

 clustered). In the figure there are several peculiar clusters of cells, 

 including from two to five or seven cells. There are no stoloni- 

 ferous processes. In comparing the feature given here by Hincks 

 with that of Nicholson's figure of Ascodictyon stellatum, and both of 

 these with my own specimen, I cannot arrive at any other con- 

 clusion than that some of the Ascodictya of the Palaeozoic rocks 

 are in some way homologous with the cluster found upon Hincks's 

 unique and solitary specimen of S. fasciculata. 



The profile of two cells, fig. 4, shows the true Stomatoporous de- 

 velopment. There are some cells in fig. 3 that are of a most pecu- 

 liar character. They differ in a few particulars from other cells ; 

 and these I have ventured to suggest may be the ocecia of the 

 colonies. I may, or I may not, be right in my conjecture on this 

 point. Unless these be ocecia, I have not been able to trace in any 

 other cells the least indication of ovarian chambers. 5 is a good 

 illustrative example of the cell referred to. Other points of struc- 

 ture are alluded to in the description of the figures. 



In the Annals and Magazine of Nat. History for June 1877, Messrs. 

 Nicholson and Etheridge, Jun., described and figured a most peculiar 

 and "anomalous genus of Palaeozoic fossils." The name given to 

 the group was Ascodictyon ; and several species were described as 

 found in Devonian and Carboniferous rocks. The systematic po- 

 sition and affinities of the fossils were not established by the authors 

 when the paper was written. Prom material in my own cabinet I 

 ventured to suggest, in a letter to Prof. Nicholson, what, judging 

 from the Carboniferous fossils, I believed to be the probable affini- 

 ties. I have now discovered in the Silurian shales of Shropshire 

 several specimens of the species given by Nicholson ; and so care- 

 fully are the characters of the Devonian fossils made out, that I 

 can trace in the Silurian specimens a most remarkable resemblance. 

 In the stellate rosette and stoloniferous processes there are differ- 

 ences so slight that I was inclined to place my own fossils under the 

 same generic and specific names, distinguishing one only with a 

 varietal term *. 



3. Ascodictyon stellatum, Nich. & Eth., Jun. 



I have only two specimens of this type. There are a few differ- 

 ences, which it may be well to indicate by giving it the varietal 

 name, siluriense, mihi. 



Colony composed of calcareous clusters of ovoid cells, having a 

 somewhat stellate character ; each cluster containing from four to 

 seven cells, which are connected together by creeping filamentous 

 cords, some of which anastomose at intervals. 



Loc. Buildwass beds, near base of Wenlock Shale, Shropshire. 



* Since this was written, I have been able to work out fuller details of this 

 most remarkable group ; and I may add that Professor Nicholson has furnished 

 me with specimens of his so-called Hippotkoa inflata, particulars of which will 

 be given in a future paper on the Polyzoa of the Wenlock Shales. 



