No. 14. — The Development of Salpa, ly Wm. K. Brooks, Ph. D. 



Sketch of Adult Structure. 



The accounts of the general anatomy of Salpa, published by Sars,* 

 Krohn,t Huxley,:}: Vogt,§ Muller,|| and Leuckart,1T leave little to be 

 done upon this subject ; but since these papers cannot be procured 

 easily in this country, and are absolutely inaccessible to the majority 

 of American students, it will not be out of place to give, as briefly as 

 possible, a description of the structure of this aberrant and highly 

 interesting genus. This seems the more important since many parts 

 of the developmental history must be unintelligible to those who are 

 not familiar with the more important peculiarities of the adult struc- 

 ture. 



The animals classed together as Tunicata agree very closely, as far 

 as general plan of structure is concerned ; and although they vary 

 greatly in form, and in the relative size, position, and degree of de- 

 velopment of the various organs, all the important structures found 

 in one may usually be found in the others ; and although the genus 

 at present under discussion departs very widely from what may be 

 considered as the typical form, those who are acquainted with the 

 structure of one of the fixed ascidians will find no difficulty in tracing 

 its homology with Salpa. 



The chief difficulty in gaining a clear conception of the relations of 



* Fauna littoralis Norvegia?. VII. 63-85. 



t Observations sur le generation et le developpement des Biphores. Ann. de Sc. Nat., 

 VI. 1846, 110. 



X Observations upon the Anatomy and Physiology of Salpa and Pyrosoma. Phil. 

 Trans. 1851. 



§ Recherches sur les animaux Inferieurs deja Mediterranee. Mem. de 1'Institut 

 National Genevois, 1854, II. 1-62. 



I! Verhand. der phys. med. Gesellschaft in Wurzburg. Bd. III. p. 57. 



H Salpa und Vervvandte. Zoologische Untersuchungen, II. 



The literature of our subject is so extensive that a complete historical sketch would 

 enlarge our account of the adult structure beyond reasonable limits; accordingly 

 authorities will be referred to, in this chapter, only in those special cases which have a 

 peculiar interest. The chapters which treat of the development will contain references 

 to the various writers, giving a history of the progress of our knowledge of this sub- 

 ject; and very complete historical sketches of our knowledge of Salpa in general may 

 be found in the papers by Huxley and Leuckart, above referred to. 



