M. Lacaze-Duthiers on the Sexes of the Alcyonavia. 453 



with numerous brown spots, which are small and rounded on 

 the hinder part of the tail and on the adipose fin. 

 The single specimen is stuffed, and 29 inches long. 



Synodontis labeo. 

 D. 1/7. A. 12. P. 1/9. V. 7. 



This species is very similar to S. xiphias ; but the snout ter- 

 minates in a large, soft, globular swelling, instead of a conical 

 pointed process. Humeral process twice as long as broad, with 

 an obtuse point behind, slightly turned upwards. Angle of the 

 mouth with a black cutaneous flap or prominence (shrivelled up 

 in our specimen). 



In all other characters this remarkable species agrees with S. 

 xiphias, as far as we can see from the single stuffed example in 

 the collection ; it is 33 inches long. 



XLIX. — On the Sexes of the Alcyonaria. 

 By M. Lacaze-Duthiers*. 



Naturalists have paid less attention to the reproduction of the 

 Coralliaria than to their external characters. At this we may 

 justly feel surprised, when we consider that in other divisions of 

 zoophytes the study of the phenomena which govern the pre- 

 servation of the species has led to the most important dis- 

 coveries. 



In the different memoirs that I have presented to the Academy 

 I have endeavoured to make known the sexual conditions which 

 are met with in widely separated types, such as Corallum, Anti- 

 pathes, Gerardia, &c. In the present paper, leaving on one side 

 the isolated species, I propose to give a summary of the more 

 general facts relating to the very natural division of the Alcyo- 

 naria ; and for this purpose I shall take my examples partly from 

 the species in which the zoanthodema is fixed, and partly from 

 the Pennatulidce, of which the polyparies always remain free. 



In Corallum the genital glands are sometimes separated, 

 sometimes united, either in the same polype or in the same 

 zoanthodema ; but, although hermaphroditism sometimes occurs, 

 it must be confessed that the separation of the sexes appears to 

 be the most usual condition; it appears even to become the 

 general rule in the entire group of the Alcyonaria, if we may 

 judge from the following genera and species — Gorgonia subtilis, 

 G. tuberculata, Muricea placomus, M. violacea, Primnoa verticil- 



* Translated by W. S. Dallas, F.L.S., from the ' Comptes Rendus' for 

 April 24, 1865. 



Ann. § Mag. N. Hist. Ser.3. Vol. xv. 31 



