272 Prof. F. M'Coy on some new genera 



Both this and the D. pristis being of considerable thickness are 

 occasionally liable to be compressed in a plane at right angles to 

 that usually seen, the two rows of cells being pressed flat against 

 each other, and so producing the form figured and described by 

 Hisinger, Portlock, Hall, &c. under the name of Graptolites sca- 

 laris ; and as the numerous specimens under my examination show 

 every stage of the accident, I do not hesitate to recommend the 

 suppression of that species. 



Abounding in the black shale of Lockerby. 



Fam. GoRGONIADiE. 



To this family I provisionally refer the two following new ge- 

 nera, from the relations of their nearest living analogues. 



Protovirgularia (M'Coy), n. g. 

 Etym. tt/jcSto?, primus, and virgularia. 



Gen. Char. Stem capillary, dichotomously branching, closely set 

 on each side with short, alternately placed pinnules, either con- 

 tracted close up to the axis in a doubly oblique alternating 

 series, or extended with a gentle upward and outward curve, 

 each pinnule transversely ridged with about five parallel cylin- 

 drical cells placed at right angles to its length. 



This is a most interesting type, as in the form of its axis and 

 the structure of the transversely ridged celluliferous pinnae, both 

 in the curved extended, and in the straight contracted states, it 

 perfectly resembles the recent Virgularia mirabilis, while by its 

 branching it approximates to the Hydroida, thus completing the 

 passage between that great group and the eight-rayed corals by 

 the present genus on the one hand and the free Hydroid Grap- 

 tolites on the other. I know but one species which resembles at 

 first sight the Graptolites ramosus of Hall, but that species has 

 only simple denticles, on one side of the branches, while this dif- 

 fers from it and all other GraptolUes by its two alternating rows 

 of moveable pinnules, transversely furrowed, apparently to contain 

 each a number of polypes, as in the recent group to which I have 

 approximated it. I have little doubt the so-called Graptolites 

 amplexicaule figured by Hall (t. 26. f. 11) may ultimately be re- 

 ferred to the same group, though the characteristic cell-furrows 

 at right angles to the upper edge of the pinnules have not yet 

 been noticed. 



Protovirgularia dichotoma (M'Coy). 



One specimen about 2^ inches long, branching twice at an 

 angle of about 30°, and shows all the pinnules extended at right 

 angles to the capillary axis with a gentle upward curvature like 



