250 DISCOVERY REPORTS 



although it is common in the North Atlantic, but they recorded a specimen of S. lyra 48 mm. long : 

 Thomson (1947) recorded S. lyra up to 50 mm., but these may well be S. gazellae from Tasmanian 

 waters: Furnestin (1953) reported a specimen of S. gazellae ( = S. lyra "gazellae "-type) 55 mm. long, 

 but has informed me that this was in fact a damaged specimen of S. hexaptera. 



Hooks. The maximum number of hooks present in S. lyra can be as high as 11, but more usually 

 10 is the figure (Fraser, 1952). 



Ritter-Zahony (191 1) gives 10 as the maximum number in S. gazellae, but in Subantarctic specimens 

 of this species I have found as many as 14. This difference is due to the fact that Ritter-Zahony did not 

 count the small hook rudiments on the dorsal side of the head, as I have done (see p. 241 ) (I have followed 

 this practice in making counts of hooks in S. lyra but still find a maximum of 1 1 only), and to the fact 

 that Ritter-Zahony's counts were on Antarctic specimens which have a rather lower maximum number 

 than the Subantarctic ones (see p. 256). 



O 10 20 30 40 50 60 70 



LENGTH MM 



Fig. 8. The number of hooks plotted against length for S. gazellae S.N. race and S. lyra. 



Johnston & Taylor (1921) record a specimen of S. lyra ( = S. gazellae) with 13 hooks on each side, 

 but other authors have agreed with Ritter-Zahony. 



The larger number of hooks in Subantarctic specimens of S. gazellae is of considerable value in 

 differentiating the species from S. lyra, and Fig. 8 gives a comparison of hook numbers and length in 

 both species. 



Corona. The shape of the corona in S. lyra is simple and pear-shaped. Fig. 9 (after Tokioka, 1940) 

 shows it in a specimen of S. lyra "lyra" -type. I have examined this feature in a fairly large series of 

 specimens of S. lyra "gazellae" -type and find it to be similar. Though exhibiting a range of variation 

 (Fig. 10) it does not depart from the general pear shape. 



Ritter-Zahony (191 1) gives two illustrations of the corona of S. gazellae (fig. 6 A, B) (Fig. 11). 

 Fig. 1 1 b is the corona drawn directly from a specimen, and Fig. 1 1 a is a simplified representation of 

 it, the latter was done because the author considered the sinuosities of outline to be due to contraction 

 of the head muscles. Although the corona is often damaged or absent in preserved specimens of 

 S. gazellae, I have been able to observe it many times among the very large number of specimens 

 which are available in the Discovery collections, and the sinuosities of outline are always present except 

 in very small specimens. I do not think they are due to contraction of the head muscles, for no evidence 



