■jTunml plrnm''] P^oyaJ Microscopical Society. ■ 83 



Snb-Fani. II. Isidin^. 

 Sclerobasic axis articulate, presenting segments wliosc composition is 

 alternately dissimilar. 



Gen. XX. Isis. 



Sp. 1. hippuris. 



2. polyacantha. 



3. moniliformis. 



4. coralloides. 



Sp. 5. elongata. 



6. melitensi.s. 



7. spiralis. 



8. corallina. 



Gen. XXI. Mopsea. 



Sp. 1. dichotoma. I Sp. 3. gracilis. 



2. encrinula. | 4. erythraa. 



Gen. XXII. Melithcea. 



Sp. 1. ochracea. 



2. coccinea. 



3. retifera. 



Sp. 4. textiformis. 

 5. tenella. 



Sub-Fam. III. Corallin.^;. 

 Sclerobasic axis entirely stony. 



Gen. XXIII. CoralUum. 



Sp. 1. rubrnm. I Sp. 3. Beckii. 



2. secundum. | 4. pallidum. 



The section of the Gorgonidse to which it is my intention to 

 confine my present observations corresponds to the first three sec- 

 tions of the sub-family Gorgoninai in the foregoing schedule of 

 classification. This group appears to me to be a very natural one, 

 comprising as it does all those Gorgonias which share in common an 

 inarticulate sclerobasic axis, and into which horny matter known 

 as corneine enters to a greater or less extent. 



For convenience sake I have provisionally applied to this group 

 the term Gorgonaceas, although it does not find its exact equivalent 

 in the rendering of the same word as made use of either by Milne 

 Edwards or Professor Kolliker. 



Commencing at the head of the appended hst, I shall now proceed 

 to describe, seriatim, the various modifications in external contour 

 and internal histological structure which are found to obtain in the 

 respective genera. 



Primnoa. — This genus, the most elegant perhaps of the whole 

 family, is at once recognized by its pedunculated calices, which are 

 armed with imbricated scales : the principal forms these scales or 

 modified spicula assume are shown at Plate XLI., Figs. 1-12 : the 

 corneous sclerobasic axis in this genus contains, in addition, a large 

 amount of carbonate of lime. The coenenchyma or intercalicinal cor- 

 tical matter is very little developed. Of the seven species alluded to 

 by ]\Iilne Edwards (leaving out P. gracilis, which I have not yet had 



G 2 



