REPOKT ON THE ACTINIARIA. 53 



reason why we should not regard the animal as conforming to the common plan of the 

 Actinias. The result would therefore be that the animal has altogether two cycles or 

 twelve pairs of septa. All the pairs of septa are quite uniform, all reach the stomach, and 

 all bear reproductive organs. In the case before us, the latter are mature testes, 

 closely filled with separate follicles of spermatozoa. As usual the tails of the spermatozoa 

 lie inwards, the heads outwards, the former converge at the same time towards a point in 

 the surface where the follicle projects into the epithelium, and where it probably bursts 

 later on, in order to empty out its contents. 



Antholoba, Hertwig. 

 Metridium, Milne-Ed wards, pro parte. Hist, des Corall., torn. i. p. 252. 



Paractidse with innumerable small tentacles, which lie on a swollen thickening of the 

 mararin of the disk ; margin of the disk lobed as in Metridium. 



After Oken had erected the genus Metridium for the beautiful Actinia Plumosa s. 

 d in it tli us (Lehrbuch d. Naturgeschichte, Th. III. Abth. 1, p. 349, 1815), Milne-Edwards 

 included in it all the forms which agreed with the typical representatives in the peculiar 

 arranp-eruent of the tentacles and in the beautiful wave-like form of the lobes which border 

 the oral disk. The probability that animals which resemble each other externally may 

 differ essentially in their internal organisation was quite overlooked. 



This is, in fact, the case, as I have proved from my own observation. It is quite 

 correct to place Metridium dianthus among the Sagartidse, since, in it as in them, only the 

 six pairs of principal septa reach the oesophagus, and, according to Gosse (Actinologia 

 Britannica, p. 20), are also furnished with acontia. Metridium dianthus differs in both 

 these points from an Actinia, which was first observed by Dana, and was erroneously added 

 to the genus Metridium by Milne-Edwards (Histoire des Coralliaires, torn. i. p. 253) and 

 Verrill (Trans. Connect. Acad., vol. i. p. 479). In this Actinia the acontia are wanting, 

 and the septa for the most part perfect as in the Paractidse. Other conditions, such as 

 the presence of a mesodermal sphincter, also show that this Actinia is a true Paractid. I 

 therefore propose to form the new genus Antholoba for these forms which externally 

 recall Metridium, but which, on the other hand, have no acontia, and are furnished with 

 numerous perfect septa as well as with a mesodermal sphincter. 



Antholoba reticulata (PI. I. fig. 9 ; PI. X. figs. 11, 12 ; PL XIII. fig. 9). 



Actinia reticulata, Couthouy, in Dana, Explor. Exped. Zoopk, p. 144, pi. iv. fig. 31, 1846 (Synopsis, 



p. 10). 

 Metridium reticulatum, Milne-Edwards, Hist, des Corall., torn. i. p. 255, 1857. 

 Actinoloba reticulata, Gosse, Actinologia Britannica, p. 24, 1860. 

 Metridium reticulatum, Verrill, Trans. Connecticut Acad., vol. i. p. 479, 1871. 



Margin of the disk fivedobed, with several thousand small tentacles, the twelve ten- 

 tacles of the first and second cycles larger than the others, and placed towards the centre at a 



