82 



BULLETIN" 100, UNITED STATES NATIONAL MUSEUM. 



i.m. 



-Y,a 



Streiff describes the cloacal musculature as resembling the usual 

 type for tubular cloacal siphons such as are seen in Apsteinia punctata. 



The gut is said by Apstein to be a compact "nucleus." Apstein's 

 description of the eye is too meager for use in our comparisons. 



The Apsteinias, as I interpret their relationships, arose from forms 

 which, like the Cyclosalpae asymmetricales, had aggregated zooids 



with great asymme- 

 try. I have so grouped 

 the species in the sub- 

 genus as to show de- 

 creasing asymmetry. 

 (See chart on p. 158.) 

 In the true Salpas this 

 asymmetry is much 

 more reduced, affect- 

 ing none of the mus- 

 cles except the atrial 

 musculature, and ob- 

 servable in the body 

 form chiefly in the 

 asymmetrical position 

 of the atrial siphon 

 and the protuberances 

 from the body. 



The Apsteinias are 

 distinguished from the 

 Ritterias (also a sub- 

 genus with asymmetrical aggregated zooids) by the fact that in the 

 former subgenus the gut of both solitary and aggregated forms is a 

 compact "nucleus," while in the Ritterias the gut of the solitary 

 form does not form a nucleus. 



Subgenus Salpa (sensu strictu) (Forskal, 1775). 



In this subgenus I include the species maxima and its variety 

 tuberculata, fusiformis and its form aspera, and cylindrica. I have 

 very abundant material of all these species. Herdman's description 

 (1888) of the poorly preserved Salpa mollis is not sufficient to allow 

 us to discuss its validity as a species, so no further reference will be 

 made to it. The species fusiformis may be taken as the type. 



The species of this subgenus are very similar to one another in 

 form and musculature. They make a compact and well-demarcated 

 group. The solitary forms of all have nine body muscles. The ag- 

 gregated zooids all show more or less asymmetrical anterior and pos- 

 terior protuberances from the body. In Salpa maxima the posterior 



Fig. 63.— Apsteinia magalhanica, aggregated form: A, dor- 

 sal view; B, ventral view. X 4 diameters. From Apstein 

 (1906, 6). 



