EEPORT ON THE TUNICATA. 7 



In 182S Aiulouin and Milne-Edwards announced their discovery of the metamorphosis 

 through which the Ascidian passes in its development from the embryo to the adult 

 form. This was also independently discovered in the various groups of Tunicata at later 

 dates by Lister, Sars, Dalyell, van Beneden, Agassiz, Krohn, and Gosse. 



The important works of Delle Chiaje, Lesueur, and Macleay also appeared at this time, 

 the latter adding considerably to our knowledge of the Bolteninse. A considerable number 

 of works of less importance, being chiefly descriptions of new species, appeared in the 

 second quarter of the century, the most notable being those of Lesson, Quoy and 

 Gaimard, Milne-Edwards and Audouin, Risso, and Ehrenberg. Broderip and Sowerby 

 first described the remarkable Chelyosoma, and Mertens his Oi/:<>jilnira, one of the 

 Appendiculariidse, about this time. Shortly afterwards (1831), some excellent observa- 

 tions upon Social and Compound Ascidians were made by J. J. Lister, and appeared in 

 the Philosophical Transactions. This author investigated the common vascular system 

 in a species which was afterwards named Perophora listeri by Wiegmann (1835). 



The curious Pelonaia, a form allied to Styela, was discovered and brought before the 

 British Association by Goodsir and Forbes in 1840, and about this time Eschricht's 

 observations upon Salpse were published in Denmark, to be followed two years later by 

 his detailed account of the anatomy of Chelyosoma. This was also the date of Milne- 

 Edwards' " Observations sur les Ascidies Composees des cotes de la Manche," one of the 

 most important memoirs upon this group of the Tunicata. 



In this country a number of short papers, chiefly by Goodsir and Forbes, Thompson, 

 Macgillivray, Carpenter, Allman, Peach, and Alder, made their appearance between 1840 

 and 1845. They contain descriptions of new species, and occasionally discussions upon 

 the systematic position and classification of the Tunicata. 



In 1845 Carl Schmidt first announced the presence in the test of some Tunicata of tuni- 

 cine, a substance very similar to cellulose, and in the following year Lowig and Kolliker 

 confirmed the discovery, and made some additional observations. An important memoir 

 1 »y van Beneden on the embryology, anatomy, and physiology of Simple Ascidians appeared 

 in Belo-ium in 1847. In the following year the first part of Forbes and Hanley's British 

 Mollusca was published. This gave descriptions of all the known species of British 

 Ascidians, many of them figured, and contained a great deal of original matter. At the 

 same time Rupert Jones' article " Tunicata" in Todd's Cyclopaedia made its appearance : 

 an excellent summary of what had been done previously, and of the state of our knowledge 

 of the o-roup at the time. Alder's Catalogue of the Marine Mollusca of Northumberland 

 and Durham, published shortly afterwards added some new species to our British fauna. 



About this time Huxley began his observations upon the pelagic Tunicates, and two 

 important papers by him appeared in 1851 in the Philosophical Transactions, one upon the 

 anatomy of Sal pa and Pyrosoma, and the other upon Appendicidaria and Dolwlwm. 

 Geo-enbaur, Vogt, H. Midler, Krohn, and Leuckart a few years later contributed further 



