I02 DISCOVERY REPORTS 



appearance. Although preserved specimens are brown, a collector's note describes one specimen as 

 ' orange ' in life. 



Internal structure. The anatomy of the species has already been described in detail, particularly 

 by Michaelsen (1900), van Name (1945) and Arnback (1950). The specimens in the 'Discovery' 

 collections are in close agreement with these accounts. But three specimens from the Palmer Archi- 

 pelago which I have assigned to the closely related C. drygalskii (Hartmeyer) require that these species 

 be compared, particularly as van Name (1945) considered them to be possibly synonymous. In 

 Table 31 I have shown their main characters, including those of 'Discovery' specimens. 



Table 31 



It appears from the comparison that only two characters separate the species: (1) the number of 

 folds on the wall of the stomach ; and (2) whether or not the intestinal loops cross the endostyle into the 

 right half of the body (Text-fig. 36A, B). 



The number of folds on the stomach seems to be a valid distinguishing character, as shown by the 

 following comparison of ' Discovery ' specimens of approximately the same size : 



C. nordenskjoldi 



C. drygalskii 



Body length (cm.) 1-3 i-8 2-1 1-5 2-3 2-5 



No. of folds on stomach 20 24 26 12 12 15 



The course of the intestinal loop is also generally a reliable character and only breaks down in 

 young specimens of C. nordenskjoldi, in which the loop has not yet grown across the endostyle to the 

 right side of the body. 



The two species also differ in distribution, C. nordenskjoldi being confined to the Subantarctic and 

 C. drygalskii to the Antarctic. 



Gonads. Cnemidocarpa and Styela are distinguished from each other mainly by differences in the 

 structure of their gonads. That these distinctions are not entirely satisfactory is shown by C. norden- 

 skjoldi. In this species the testis follicles are closely applied to the sides and parietal surface of the 

 gonad and are enclosed along with the ovary within a common membrane (Fig. 36 C, D), thus agreeing 

 with the condition in Cnemidocarpa (see van Name, 1945, pp. 262-3). When the testis is fully developed, 



