36 G. r. MATTHEW ON THE 



has been found. On the lower St. Lawrence at various stations from Mataue to Cape 

 Rosier the species has been met with. Examples from these places, belonging to the col- 

 lections of the Geological Survey of Canada, have been examined and determined by Prof. 

 Charles Lapworth. 



Another district where the species has been found is at Barrasois River, in Cape 

 Breton. At the latter place it is said to occur (as at St. John) in company with "Oleni."' 



Among the examples of this species found in the black shales of the Bretonian Divi- 

 sion at St. John three varieties may be observed. 



Var. confertum. Linrs. Mss. ? 



Dr. Brogger in his work on the Cambrian and Ordovician rocks of Norway mentions 

 several varieties of this species,- and among them that abov'e named. This, he says, has a 

 net-like web, luliich is very fine and close, for ivhicli reason the threads connecting the branches are 

 alivays very fine. 



This description agrees well with the characters of a form which is particularly pre- 

 valent in the lower beds at St. John containing Dictyonema (Div. 3 b). It is distin- 

 guished from the more common form of the typical Dictyonema beds (Div. 3 c) by more 

 frequently assuming the vasiform shape, as distinguished from the broad funnel-formed 

 hydrosomas, which are the more common in the typical beds. Not only are the connect- 

 ing threads very fine, but they are more numerous than those of the common form. In 

 this variety the branches of the hydrosoma are nearly a millimetre apart, and there are 

 from five to seven connecting threads between the branches in a space of a centimetre. 

 From twelve to fourteen hydrothecœ are found in the space of a centimetre. 



As regards the number of connecting threads between the branches, this form agrees 

 with that mentioned by Tullberg as occurring at Fagelsang, in Sweden. (See p. 34.) 



Yar. Acadicum, n. var. 



This variety in its general outline agrees with the typical form of Sweden, and no 

 doubt represents it here. Although sometimes vasiform, it is more frequently funnel- 

 shaped, and the mesh of the hydrosoma is more open than with the last. The branches 

 are straighter and divide more frequently, and the connecting threads are stronger. 



In this variety the branches vary in number from two in the space of about 3 milli- 

 metres to three in a space of 4 millimetres. There are usually from four to five threads 

 between the branches in the space of 1 centimetre, and from sixteen to seventeen hydrothecœ 

 are found in the same space along the branches. 



This variety is rare in the lower layers, where var. confertum occurs, but very common 

 in some beds at the typical horizon (Div. 3 c). It represents the typical European form, 

 but differs in having more numerous hydrothecœ on its branches. Tullberg mentions 

 that the Scandinavian variety (the type of the species) has from 10 to 15 hydrothecœ in a 

 space of 10 millimetres.' 



' By " Oleni " the later allied forms, Parabolina, etc., may be intended. I confidently anticipate tlie discovery 

 of the Peltura fauna beneath the beds with Dicli/onema flahcWforme on the Lower St. Lawrence. 

 " "Die Silurischen Etagen," 2 und 3, p. 35. 

 ' Graptolites described by Hisinger, p. 20. 



