GULF OF MEXICO 



497 



which formed the genus Salpa in old classifications 

 but are now commonly divided into several genera 

 or subgenera. They are transparent jelly-like 

 creatures of more or less ovate form, having 

 transvei-se muscle bands which contract and enable 

 them to swim slowly. They are found in the open 

 sea as well as along the coasts. Some of them 

 appear at intervals in immense swarms. The 

 salpas afford a striking instance of alternation of 

 generations; one of solitary individuals alternates 

 with one of aggregated individuals budded off 

 in a chain in which they may remain connected 

 together for a time. Because of the watery, un- 

 substantial character of their tissues, including 

 the test, they are of small value as food for other 

 animals. 



Among the species found in the Gulf of Mexico 

 are: Salpa (Thalia) democratica, a small but 

 often abundant species, S. (Pegea) conjoederata, 

 S. (Salpa) cylindrica, S. (Salpa) fusiformis, 

 Cyclosalpa floridana. See Metcalf 1918. 



Another pelagic genus occurs in the Gulf, 

 Pyrosoma, a compound form in some respects 

 intermediate between the Ascidiaeea and the 

 Thaliacea and sometimes included in the former 

 group. It forms gelatinous tubular colonies closed 

 at one end which are very luminous at night. 

 See Metcalf and Hopkins 1919. 



No monograph dealing exclusively with the 

 Tunicata of the Gulf of Mexico has ever been 

 pubhshed. The information about them is widely 

 scattered, much of it in works dealing chiefly with 

 those of other regions or mainly with animals of 

 other groups, often in foreign language or in back 

 volumes of scientific periodicals that few libraries 

 have available. Most tunicates are animals of 

 wide distribution; many occur in both the Old 

 and New World and were originally described in 

 European works, and the insufficient descriptions 

 and obsolete nomenclature used in the older books 



will often be a cause of confusion. However, a 

 nearly complete bibliography of the systematic 

 literature on the American ascidians, including 

 those of the Gulf of Mexico, will be found in the 

 work by Van Name (1945) listed below. Since 

 that date little of importance has (1950) been 

 published. 



The following works will probably be found the 

 most useful to consult for recent information on 

 the Gulf of Mexico Tunicata and references to 

 other literature on them. Several important 

 general works are also listed. 



BIBLIOGRAPHY 



Berrill, N. J. 



1932. Ascidians of the Bermudas. Biol. Bull. 62: 77-88, 



figs. 1-5. 

 1950. The Tunicata, with an account of the British 

 species. Roy. Society London, pp. 1-.354, figs. 1-120. 

 Brooks, W. K., and Kellneb, C. 



1908. The pelagic Tunicata of the Gulf Stream. Carne- 

 gie Inst. Washington Pub. 102, pp. 73-94, figs. 1-3, 

 pis. 1-8. 

 Metcalf, M. M. 



1918. The Salpidas: a taxonomic study. U. S. Nat. 

 Mus. Bull. 100, 2 (2): 3-193, figs. 1-150, pis. 1-14. 



and Hopkins, H. S. 



1919. Pyrosoma: a taxonomic study. U. S. Nat. Mus. 

 Bull. 100, 2 (3): 195-275, figs. 1-9, pis. 15-36. 



Plough, H. H., and Jo.ves, N. 



1939. Edeinascidia tortugensis, species nova. With a 



review of the Perophoridae (Ascidiaeea) of the Tor- 



tugas. Carnegie Inst. Washington Pub. 517, pp. 47- 



60, figs. 1-3, pis. 1-8. 

 Thompson, H. 



1948. Pelagic tunicates of Australia. Council Sci. 



Indust. Res. Melbourne, pp. 1-196, figs. 1-19, pis. 



1-75. 

 Van Name, W. G. 



1930. Ascidians of Porto Rico and the Virgin Islands. 



Sci. Surv. Porto Rico and Virgin Islands 10: 403-512, 



figs. 1-73, pis. 5-8. 

 1945. The North and South American ascidians. Bull. 



Am. Mus. Nat. Hist. 84: 1-476, figs. 1-327, pis. 1-31. 



