394 CARBONIFEROUS LAMKLLIBRANCHIATA. 



Dimensions. — PI. XLII, fig. 19, from the Carboniferous Limestone of Malaliicle, 

 CO. Dublin, measures — 



Antero-posteriorly . . . .43 mm. 



Dorso-ventrally . . . .20 mm. 



From side to side . . . .16 ram. 



Localities. — England : the Carboniferous Limestone of Eskerhouse and Hill 

 Stebden, Yorkshire, and Poolvash, Isle of Man ; the Redesdale Ironstone, 

 Northumberland. Scotland : the Upper Limestone series of Boghead, and Linn 

 Spout, Dairy; the Lower Limestone series of Craigenglen, Campsie, and Hind 

 Og Glen, Dairy; shore east of Ardross Castle, Calciferous Sandstone series. 

 Ireland : the Carboniferous Limestone of Malahide, co. Dublin. 



Ohservations. — 8. strlato-granulatus has somewhat the shape and general ap- 

 pearance of S. tricostatus ; but in the very best preserved specimens of the 

 latter species I have never been able to make out any tubercles or granules on 

 the surface. In addition, the escutcheon of 8. striato-gramilatus is very much 

 larger and broader than that of 8. tricostatus. The posterior end is narrower 

 and more squarely truncate, the hinge-line much longer, and the cost[e on the 

 dorsal slope are less well marked. The lines of growth are generally more 

 rugged, and not so fine and regular. The granulations on the surface are very 

 like those found in Edmondia sulcata, Allorisma sulcata, and Tellinoniorpha 

 cnneata, and have the same arrangement; but the absence of escutcheon and 

 lunule at once serves to distinguish the genus Edmondia from 8anguinoUtes ; and 

 the diagnostic differences between 8anguinolites and the other genera have been 

 pointed out above (page 365). 



8. Omalii, de Ryckholt, sp., figured by de Koniuck, is one of the few species 

 of the genus which is narrower behind than in front; but no mention is made of 

 any radiating lines of tubercles, and the shell is much attenuated behind by the de- 

 pression of the upper border. 



I am of opinion that the specimen which de Koninck has referred to 8. 

 tricostatus really belongs to the species under discussion. He figures in a diagram- 

 matic sort of way the decussating lines, and describes them as follows (ojj. supra 

 cit., p. 85): — " Toute la surface est ornee d'un reseau forme de minces plis 

 d'acroissement, quelquefois un pen lamelleux, qui coupent en travers de fines 

 stries rayonnantes a peine perceptibles a la simple vue et produisant aussi une 

 reticulation qui ne m'a ete offerte par aucune autre espece." 



M'Coy also seems to have confused the species, for he says, in his remarks on 

 F. tricostatus (uj). cit., p. 507), " When the periostraca is [are] preserved, rows of 

 minute dots are seen radiating from the beak across the concentric plicae." 



