NOTES AND MEMORANDA. 281 



or be filled up with siDougy tissue traversed by cross-partitions ; 

 secondary, calcific masses may also be found in the cavities of the axis. 

 The third j^art of the paper is classificatory : the author divides 

 the various families of the Alcyonaria into three chief groups, as 

 follows : — 



I. — Polypes never united into a colony. 



Fam. 1. Haimeida. 

 II. — Colonies are formed, but the individual polypes remain independent, 

 and are only united by stolons or by plate-like expansions. 

 Fam. 2. Cornularida. — Spicules separate. 

 „ 3. Tubiporida. — Spicules united into a continuous ske- 

 leton. 

 III. — The coenenchyma is well developed, and the polypes appear only as 

 organs of the colony. 



a. Mesoskeleton only developed. 



Fam. 4. Alcyonida. — ^'kcleion spicular. 

 „ 5. Pscudaxonia. — Skeleton continuous. 

 „ 6. Helisporida. — Main part of skeleton calcified ; no 

 sjiicules. 

 6. Both meso- and ectoskeleton developed. 



Fam. 7. Pennatulida. — Free-swimming; digestive cavities 

 long. 

 „ 8. Axifera. — Fixed ; digestive cavities short. 



New Species of Isis. — A new species — Isis Neapolitana — of the 

 interesting Alcyonarian order Isidacece has been recently discovered by 

 V. Koch, who gives an account of its anatomy,* together with the 

 following diagnosis : — 



" Polypary about 1 metre high, ramified, attached to rocks, &c. by 

 means of an irregularly lobed basal plate, branches springing from the 

 horny internodes. Calcareous joints of the axial skeleton white, cylin- 

 drical ; on the thicker stems about 8 mm. ; on thinner branches about 

 16 mm. long, strongly ribbed. Internodes dark brown, becoming 

 shortened with the decrease in thickness of the stem, from 2 • 5 mm. 

 to • 3 mm. in length. Coenenchyma thin, greyish-white, containincf 

 calcareous spicules only in the bases of the polypes. Nutrient canals 

 twice as numerous as the longitudinal grooves on the calcareous joints. 

 Polypes scattered over the branches, about 3 mm. long, well provided 

 with smaller and larger spicules ; outer wall of tentacles also containing 

 spicules. Polypes very slightly contractile. Habitat, Gulf of Naples. 



The paper is accompanied by a plate, illustrating the anatomy of 

 the species. 



Gorg-onia verrucosa — In a short paper on the anatomy of this 

 species,t v. Koch records the important discovery of a layer of eijithe- 

 lial cells between the horny axis of the zoanthodeme and the ccBnen- 

 chyma. He has found the same thing in other Gorgonice, and consi- 

 ders it certain that, in some at least of the horny corals, the axial 

 skeleton is a secretion of an epithelium derived, in all probability, 

 from the ectoderm. 



This discovery is of great interest, as, according to most observers, 

 the axial skeleton of Gorgonidce is formed from the connective tissue of 

 the coenenchyma ; Koch himself, indeed, assigns this origin to it in Isis. 

 * 'Morphol. Jahrb.,' iv. (1878) 112. f Ibid., 269. 



