vol. 2, pt. 2.] A TAX0N0MIC STUDY OF THE SALPIDAE METCALF. 



55 



In the elongation of the body and the large number of the body- 

 muscles, the Ritterias have passed distinctly away from the Cyclo- 

 salpa condition. 



The aggregated form of Ritteria retracta is unknown, except from 

 one inadequate figure by Apstein (1906, b) of a small individual from 

 the stolon of what he took to be " Salpa amboinensis," but which 

 Ihle (1910) showed to be of the species retracta. No description of 

 the aggregated zooid accompanies this figure, but it is sufficient to 

 indicate close resemblance to the aggregated form of Ritteria am- 

 boinensis. 



Apstein (1906, b) describes as Salpa amboinensis a form which, as 

 Ihle (1910) has pointed out, is clearly Ritter's retracta. 



RITTERIA PICTETI (Apstein, 1904). 



Salpa picteti Apstein, 1904, a. 

 We have not as complete knowledge of this 

 species as of Ritteria retracta, no description o 

 the oral or atrial muscles, as seen in side view, 

 being given. Apstein's figures (1904 and 1906, a) 

 of dorsal and ventral views (figs. 26 and 27) 

 show in one specimen 21 body muscles (Ap- 

 stein, 1904), the presence of an incomplete in- 

 termediate muscle as in R. 

 retracta not being quit certain 

 from either the figures or de- 

 scriptions. All are inter- 

 rupted ventrally (fig. 27) . In 

 a second specimen, collected 

 by the Deutsche Tiefsee-Ex- 

 pedition, Apstein (1906, a) 

 shows 26 body muscles (fig. , 

 27) , there being here the same 

 doubt as to the presence of 

 an incomplete intermediate 

 muscle. If I interpret him 

 correctly, Ihle's description 

 (1910) of his single specimen 

 of this form indicates the 

 presence of an incomplete in- 

 termediate muscle, which, 

 like the body muscles, is 

 interrupted ventrally. Ihle's 

 specimen had 24 body muscles on the right side and 25 on the left. 



-\-en. 



TXT 



"'? 



a.o. 



FlQ. 26.— RlTfERIA PICTETI, 

 SOLITARY FORM, DORSAL VIEW. 

 X 2 DIAMETERS. FROM AP- 

 STEIN (1904). 



a.o. 



Fio. 27.— Ritteria picteti, 

 solitary form, ventral 

 view, natural size. 

 From Apstein (1906, 6). 



