THE BRITISH FOSSIL BRACHIOPODA. 373 



For the family Spiriferid^e the same German palaeontologist proposes several sub- 

 families (op. ciL, p. 498 et seq.) : 



1. Sub-family Suessiin^e, Genus Spiriferina, d'Orb. 



2. Sub-family Delthyrin^e, Genus Spirifer, Sow. 



3. Sub-family MartiniinjE, Genus Martinia, M'Coy, and Martiniopsis, Waagen. 



4. Sub-family Reticulariin^, Genus Beticularia, M'Coy. 



I think Dr. Waagen correct while generically separating those species of Spiri- 

 feridcB with a perforated shell-structure from those that have a fibrous and not punc- 

 tured shell. This view is also taken by Prof. Bayle, and for which reason he maintains 

 the genus Martinia, M'Coy. This character was not, however, known to M'Coy when in 

 1 844 1 he proposed his genus, and did so on the mistaken supposition that the spiral 

 appendages were small, but which is not the case, as has been amply proven by myself 

 and from Mr. Glass's many and perfect preparations of the spirals of M. glabra, of 

 which I have given figures in the first part of my ' Carboniferous Supplement.' 



We are, therefore, gradually advancing in our knowledge of the characters of the 

 spiral-bearing genera and species, and I have every hope that with renewed exertions still 

 more information will be acquired, and that with time a correct and permanent grouping 

 of the genera will become possible. 2 Dr. Waagen when treating of his genus Martiniopsis 



1 ' Synopsis of the Characters of the Carboniferous Fossils of Ireland,' p. 139, woodcut, fig. 22, 1844. 



2 Previous to leaving the subject in connection with the Spiriferidce I would mention that for many 

 years past it has been observed that in some species of long-hinged forms of Brachiopoda there are present 

 numerous small denticulations, as well as vertical lines on the area, proceeding from each of these 

 denticulations. These I figured in Strophodonta demissa (Conrad) in the 'Geologist' for March, 1859 ; 

 and the same thing has been observed in other species by more than one palaeontologist. Recently, 

 however, while examining some weathered fossiliferous shales from the Lower-Carboniferous strata of 

 East Kilbride, in Lanarkshire, Mr. John Young's attention was attracted to some fragments of the valves 

 of Spirifera trigonalis, Martin, in which he noticed, on the hinge-line of the dorsal valve, a row of 

 small, rounded, hollow pits, and on the hinge-line of the ventral valve corresponding projecting rounded 

 denticles, which fitted exactly into the little hollows on the hinge-line of the opposite valve, and thus 

 in a measure assisted to steady the valves, especially when the hinge-line was long and the teeth not very 

 large. Mr. Young has published the results of his researches on this subject in the ' Geological 

 Magazine,' new series, decade iii, vol. i, p. 18, 1884. He says that "the denticles, when looked at 

 externally, are nearly as numerous and of much the same size as those 



seen in many of the hinge-lines of shells of the genus Area, only in ^^2?W3litSte^ 



this genus the teeth are the same in each valve and lock into each ^^^^^^^^^^^^W^\f~-^ 



other. The denticles, as already stated, project from the outer edge 'jMim^M^W ^SuB ^^ ^ 

 of the hinge-line of the ventral valve, which is seen to be bevelled 55iiii ""™™ s ^ ^Tv: 

 from within outwards so as to present a moderately sharp edge, and Spirifera trigonalis (Martin), after 

 on this edge the denticles are situated. On a specimen measuring one Diagrain , naJsizTto show the den- 

 inch and three quarters in length along the hinge-area thirty-five of ticulated hinge-line in the ventral 

 these denticles may be counted on each side of the central triangular th/hinge-line of th"dorsal vafve.' 

 fissure. It had long been noticed that in the shell-structure of the 



external surface of the hinge-line area in the ventral valve of many of the species of Spirifera as well as in 

 others of the straight-hinge Brachiopods, there exists a series of vertical lines or tubes, slightly inclined 



