ANTARCTIC ROTIFERA 49 



found, which may belong to this species or to C. angularis (Plate XII., Figs. 12c-12c). 

 Each of these eggs was found with the jaws of the contained young so well grown 

 that the numerous teeth could be seen. As there are only the two species known at 

 Cape Royds which have many teeth, it is practically certain that these eggs belong to 

 them, but as they were never found in the bodies of the rotifers it cannot be determined 

 to which each belongs. 



Callidina angularis, sp. n. (Plate XII., Figs. 12a I2d) 



Specific characters. Small, yellow, much widest in central trunk ; strongly 

 nodose from the lateral projection of certain segments, from the neck to the preanal : 

 trunk strongly plicate, and stippled (except head, neck, and foot). The head is widest 

 at the cheeks, and the corona is distinctly smaller, and about equal in diameter to the 

 neck. Rump narrower than the fourth central segment, its two segments distinct. 

 Foot short, of three segments. Spurs small, divergent, acuminate and acute. Food 

 moulded into pellets. Jaws narrow, teeth many. 



General description. Length when feeding about ^^ inch, rather greater 

 when creeping. The diameter of the corona is about -^ inch (50 ju), and of the 

 widest part of the trunk about ^<y inch (100 M ). The rostrum is short and broad 

 and the antenna short. There are from eight to ten teeth in each jaw, and they 

 diminish rapidly in thickness towards the posterior end of the jaw. The anterior 

 edges of the three segments succeeding the neck are strongly produced outward, 

 giving a nodose appearance to the anterior trunk. The mid-trunk is also laterally 

 produced into an angle. The fourth central and preanal segments are also produced 

 at their posterior edges. The trunk has few broad clearly marked folds. The 

 preanal has two folds near the middle line. The three toes are short and obscure. 



The upper lip is a somewhat triangular area. The central portion forms a pointed 

 arch, or may be rounded or slightly cleft. The collar is very inconspicuous. The 

 voluminous stomach is red or brown or pale yellow. The pellets are very obscure. 



Habitat. In most of the lakes at Cape Royds. 



Reproduction. The absence of living young makes it practically certain that the 

 species is oviparous. Associated with it were eggs (already referred to under 

 C. constricta) which could only belong to one of these species. 



Affinities. C. angularis is undoubtedly derived from C. constricta. There are so 

 many points in common that they were for long considered to be identical. The out- 

 line of a Bdelloid rotifer can vary so much during the different movements that it was 

 considered inadvisable to put much importance on the angular outline of this species. 

 It was only when the peculiar form was found to be always associated with a stippled 

 skin that it came to be regarded as distinct from G. constricta. 



Eggs. As to the eggs of this species, see remarks under C. constricta. 



BRIT. ANTARCT. EXPED. 1907-9. VOL. I. G 



