Miscellaneous. 493 



Colonial Muscular System. — Besides the muscular cords just 

 mentioned, there exist in the common transparent substance mus- 

 cular bands which are by no means so well defined, and which 

 unite the individuals to one another in the longitudinal direction. 

 Panceri has described their course with considerable exactitude, but 

 without knowing their origin. These muscular bundles originate 

 in the transparent substance itself, in which we see them diverging 

 at certain points; and they seem to be formed at the expense 

 of the actual cells of this substance modified in a peculiar manner. 

 The normal constituent cells of the common transparent substance 

 are stellate. 



0)1 the Elczohlast. — Salensky has endeavoured to show that the 

 elaeoblast of the Salpce may be the altered representative of the tail 

 of the Appendicularice and the tadpole-larva) of Ascidians. As re- 

 gards Pijrosoma, this hypothesis is inadmissible. The elaeob.last, in 

 fact, acquires in Pyrosoma the form of a ring surrounding the ger- 

 minative extremity of the endostyle. It is therefore no longer a 

 simple organ as in the Salpce. By its form and relations it cannot 

 represent the tail of the Ajjpenclicidance. 



Its function appears rather to be phj'siological. It enlarges so 

 long as the bud remains attached to the parent, and diminishes from 

 the moment when separation is efi'ected, until that in which the 

 young ascidiozoid, being brought into communication with the outer 

 world, can live on its own account ; it then disappears altogether. 

 I do not think it plays any part, even a subsidiary one, in gemma- 

 tion. In fact, it has completely disappeared at the period when 

 gemmation has only just commenced. In all probability it acts as 

 a reserve for the young animal at the time when its nutrition ia 

 stiU null or insufficient. 



On the Alternation of Generations. — If we desire to bring toge- 

 ther as much as possible what takes place in the Salp(X and what 

 occurs in Pyrosoma, we must take as equivalent terms, on the one 

 hand, the agamic Salpa, and, on the other, the Cyathozoid. We 

 have then, in the two cases, two asexual individuals producing by 

 gemmation a whole series of individuals which differ from them in 

 form, are alike, and sexual. The whole difference then lies in the 

 fact that, while the sexual Salpce cannot bud, the sexual Pyroso- 

 mata are capable of producing by gemmation other individuals, but 

 similar to themselves. — Comptes Bendus, April 25, 1881, p. 1013. 



Investigation of certain Points in the Anatomy of Sternaspis 

 scutata. — Second Note *. By M. Max. Rietsch. 



■ The vascular system of Sternaspis is very complex and interest- 

 ing ; it may be summed up by saying that it includes a dorsal 

 vessel and a ventral system. 



The dorsal vessel follows the stomach, upon which it rests, in aU 

 its contours ; it is much narrower behind than in front of the bran- 



* See ' Annals; May 1881, p. 426. 



Ann. & Mag. N. Hist. Ser. 5. Vol. vii. 36 



