W. K. BROOKS ON THE GENUS SALPA. 9 



Salpa costata there are twenty. They may be continuous, as in Salpa 

 pinnata, Plate XLI, Fig. 5, or interrupted as in Salpa costata, Plate IV, 

 Fig. 4. They may be independent as in the last species, or united in sets 

 as in Salpa democratica, Plate I. They may be restricted to the dorsal 

 surface of the body, as in Salpa africana, Plate IV, Fig. 2, or they may 

 be completely closed rings passing entirely around the body like the 

 hoops around a barrel, as in the solitary form of Salpa democratica, 

 Plate II. 



Leuckart says (I, p. 15) that while the gap may be so short that it 

 is not visible without a microscope, they are always interrupted on the 

 middle line ; but I am at a loss to find the basis for this statement, for 

 the fibers may be traced across the middle line, without any break, in 

 many species. He also says, p. 16, that as they never cross the ventral 

 middle line they are never complete rings, and this statement has been 

 repeated over and over again until it has found its way into all the text- 

 books and scientific memoirs, notwithstanding the fact that most of them 

 are completely closed, dorsally and ventrally, in the most familiar and 

 abundant species, the solitary Salpa democratica, Plate II. 



This error has been most persistent, and it has been made the basis 

 of the fundamental definition of the whole Salpa family, for which Glaus 

 has proposed the name Desmomyaria, and Herdman the name Hemi- 

 myaria, to distinguish them from the Doliolums, for which Gegenbaur 

 has proposed the family name Cyclomyaria. 



Even if this difference between Salpa and Doliolum were absolute, 

 the selection of a characteristic so very variable as the form of the loco- 

 motor muscles as a basis for fundamental classification would be most 

 unwise ; and, as a matter of fact, some of the muscle-bands of Doliolum 

 are incomplete, and some of them, in at least one species of Salpa, com- 

 plete. In the first generation or "Amme" of Doliolum the seventh body- 

 muscle is incomplete dorsally, and in the median "Pflegethiere" it is 

 incomplete ventrally, while the lateral buds or "Ernahrungthiere" depart 

 very widely from the cyclomyarian type. 



So far as I am aware, Traustedt is the only modern writer on Salpa 

 who has described the muscle-bands of Salpa democratica as complete 

 circles. In his description of this species, p. 365, and also in his descrip- 

 tion of the variety flagellif era, p. 369, he states the facts correctly, but while 

 his draughtsman, Cordts, has figured Salpa democratica correctly, Plate 

 II, Figs. 25 and 26, he has followed tradition in his figure of Salpa flagelli- 

 fera, Plate I, Fig. 12, rather than nature and Traustedt, and has drawn 



