128 Mr. F. M'Coy on some new genera and species of 



from these the vertical lamellae radiate to the circumference, 

 where they are connected by the small transverse vesicular 

 plates forming the narrow external cellular zone. 



I propose this genus for a number of corals exceedingly 

 abundant in the mountain limestone, but hitherto classed by 

 Prof. Phillips, Mr. Lonsdale, and others with Lithodendron. This 

 latter genus was originally proposed by Schweigger (Beobach- 

 tungen, &c. tab. 6) to include, 1st, the Oculina of Lamarck, in- 

 cluding the type of Blainville's Dendroplirjllia ; and 2ndly, a di- 

 vision, which allowing the previously constituted genus Oculina 

 to stand for the first division, becomes the real type of his ge- 

 nus, and the four references he gives to Esper's ' Pflanzenthiere ' 

 as examples of this genus are typical examples of the group 

 subsequently named Lobuphyllia by Blainville ; this latter name 

 therefore becomes a mere synonym of Lithodendron and should 

 be laid aside, unless, as many writers seem inclined, it be used 

 for the short, wide species with lobed discs, and thus leave Litho- 

 dendron for the more slender cylindrical forms : although there 

 is no clear line of separation between the groups, it may be con- 

 venient to retain both names for those extreme forms, but in no 

 case can the Siphonodendra of the mountain limestone be 

 brought in any close relation with those recent and mesozoic 

 types. The differences are briefly these : 1st, Siphonodendron 

 increases by lateral buds, — Lithodendron by a lateral elongation 

 and gradual division of the old cup and dichotomous fissure of 

 the stem ; 2nd, Siphonodendron has a narrow tubular axis and 

 wide conoidal diaphragms, while Lithodendron has a large cel- 

 lular axis and no diaphragms. I have illustrated those points in 

 the accompanying sketch. Cladocora of Ehrenberg agrees in ex- 

 ternal form and mode of branching with Siphonodendron, but has 

 the internal structure here represented in Lithodendron. 



' Cladochonus hrevicollis (M'Coy). 



Sp. Char. Slender stem- like neck of each cell about 1 line long 

 and half a line in diameter, the upper end suddenly swelling 

 to a cup-shaped cell about 2 lines long and 1 line in diameter, 

 curving downwards at an angle of about 135°, the point of 

 junction of the cup and the stem giving origin, at an angle of 

 45°, to the stem of a second cell similar to the first, but incli- 

 ning in the opposite direction, and in like manner giving ori- 

 gin from its upper convexity to a third and that to a fourth, 

 &c. perfectly similar cell, forming together an erect, regularly 

 zigzag corallum. 



From its regularly angular mode of growth or connexion of 

 the large drooping bell-shaped cups, inclining in opposite direc- 



