10 BRITISH STROMATOPOROIDS. 



replaced by carbonate of lime in the process of fossilisation. He describes 

 S.polymorpha, Goldf., var. constellata, which he regards as identical with Stromato- 

 pora verrucosa, Goldf. 



In 1862, Mr. Billings described a Stromatoporoid from the Black-River Lime- 

 stone, under the name of Stromatopora compacta (' Palaeozoic Fossils,' p. 55). He 

 at first referred the Stromatoporoids to the Amorphozoa ; but in a later portion of 

 the same work he expressed the opinion that they are Corals, and are allied to 

 Fistulipora. 



In 1865, Professor Hyatt expressed the opinion (' Amer. Journ. Sci. and Arts ') 

 that the singular genus Beatricea, Bill., should be placed among the Cephalopoda, 

 of which it should be regarded as the type of a special family. 



In 1866, Professor Winchell published an important paper on the structure and 

 affinities of the Stromatoporoids (' Proc. Amer. Assoc, for the Advancement of 

 Science,' 1866, p. 91). In this memoir, the author not only discusses the minute 

 structure and systematic position of the Stromatoporoids, but also gives descrip- 

 tions of four species from the Devonian Rocks (Hamilton group) of Michigan and 

 Ohio. 1 The species described are named 8. pustulifera, 8. monticulifera, 8. nux, 

 and 8. co3spitosa ; but they are, unfortunately, not figured. The two former are 

 stated to be of the general type of 8. polymorpJia, Goldf. ; and it is interesting to 

 note the statement of the author that, having examined "ship-loads" of specimens, 

 he has " never detected evidence that they were in any sense encrusting." Stro- 

 matopora nux is said to be of the same type as 8. concentrica, Goldf. ; and 8. 

 ccespitosa is a wholly aberrant form, for which a new genus (Idiostroma) is 

 proposed. As regards the general affinities of the Stromatoporoids, Professor 

 Winchell comes to the conclusion that they constitute a peculiar group of the true 

 Corals, with relationships to the Cystiphyllidce and Gyathophyllida}. The following 

 is the arrangement of the Stromatoporoids and their subdivisions as proposed by 

 Winchell. 



" Family, Stromatoporidm. — Polyps isolated or confluent; exserted, never 

 forming a cup ; secreting a corallum which consists of a series of concentric layers 

 (or diaphragms) of vesicular tissue, separated and perforated by vermicular rami- 

 fying passages, which are either radially or confusedly disposed. Mural system 

 wanting ; lamellar structure distinctly present only in the higher forms. 



"Genus, Idiostroma (n. gen.). — Polypi completely isolated, forming branching 

 masses ; lamellar system represented by a radial structure. 



" Species : I. ccespitosum, I. gordiaceum. 



" Genus, Coenostroma (n. gen.). — Polypi confluent, but individualised, forming 

 elongated or spheroidal compound masses ; diaphragms common and continuous 



1 These species were originally described by Prof. Winchell in his ' Eeport on the Grand Traverse 

 Region,' a work to which I have unfortunately not had access. 



