40 ANATOMY AND PHYSIOLOGY OF SALPA AND PYROSOAIA 



Forskahl, pyramidalis of Quoy and Gaimard. They are described 

 by Sars as 5. spinosa and 5. mucronata, or rather as 5. spinosa, proles 

 solitaria, and 5. spinosa, proles gregaria. This, however, begs the 

 question as to the truth of Chamisso's theory, and I shall therefore 

 prefer to name the two forms I observed simply Salpa A and 

 Salpa B. 



At Cape York, and only there, these two forms were always 

 obtained together. They were of about the same size, but so totally 

 distinct in appearance, that, had they belonged to any other genus, 

 they would have been justly regarded as separate species. 



7. Salpa A, Plate XV. [Plate 5], fig. i. — The body is gelatinous, 

 transparent, and colourless, except the nucleus (z), which has a deep 

 reddish-brown tint. It has a general square prismatic shape, and 

 is abruptly truncated and somewhat convex at each extremity. The 

 posterior extremity is provided with eight horn-like processes, which 

 project backwards. Two of these are short and hook-like, placed one 

 before the other in the median line at the posterior part of the 

 superior surface. On the upper part of the lateral surfaces there 

 is, on each side, a short process. From about midway between the 

 upper and lower edges of this surface, a long, conical process curves 

 upwards and backwards ; these processes are distinguished from the 

 others by containing a c^cal process of the system of sinuses in their 

 base {y). 



Close to the lower edge of the lateral surfaces there is another 

 .short process like the uppermost one. 



The respiratory apertures are wide and provided with valvular lips. 

 The posterior {b) is narrower, and has the valvular lip more marked. 



The ganglion (d) is less than one-fourth of the length of the body 

 distant from the anterior respiratory aperture. 



The otolithes are four in number, hemispherical, and with a dark 

 blackish brown coloured spot on their external surface, Plate XVI. 

 [Plate 6] fig. 5. 



The endostyle (c) is nearly half the length of the body (reaches as 

 far as the sixth muscular band, counting from before backwards). 



The outer surface of the integument is everywhere covered with 

 minute asperities, like little prickles. 



The muscular bands {k) are seven in number, and, with the excep- 

 tion of the anterior and posterior, completely encircle the body of the 

 animal. This form was always free and solitary.^ 



8. Salp(B B, Plate XV. [Plate 5] fig. 2, on the other hand, is thus 

 characterized. The body is subovoid, smaller at the posterior ex- 



^ The statements of Meyen {op. cit. ) to the contrary are certainly erroneous. 



