. Fig. 1. Fig- 3- Fig. 4. Fig. 1. A 'typical' hook from S. gazellae (a) and a 'secondary' hook from S. lyra (b). (From Ritter-Zahony, 1911.) Fig. 2. The tip of a hook of S. 'lyra'. (From Johnston & Taylor, 1921.) Fig. 3. A hook of S. furcata'. (From Fowler, 1905.) Fig. 4. A specimen of S. furcata. (From Fowler, 1905.) a young specimen of S. lyra and still be correct. Neither the existence of claw tips in S. gazellae hooks nor the presence of simple type hooks in certain specimens of S. lyra affect the validity of Ritter- Zahony's statements. It is upon Johnston's & Taylor's evidence th
. Fig. 1. Fig- 3- Fig. 4. Fig. 1. A 'typical' hook from S. gazellae (a) and a 'secondary' hook from S. lyra (b). (From Ritter-Zahony, 1911.) Fig. 2. The tip of a hook of S. 'lyra'. (From Johnston & Taylor, 1921.) Fig. 3. A hook of S. furcata'. (From Fowler, 1905.) Fig. 4. A specimen of S. furcata. (From Fowler, 1905.) a young specimen of S. lyra and still be correct. Neither the existence of claw tips in S. gazellae hooks nor the presence of simple type hooks in certain specimens of S. lyra affect the validity of Ritter- Zahony's statements. It is upon Johnston's & Taylor's evidence that the case put forward by Tokioka (1939) and Thomson (1947) for the inclusion of S. gazellae in the synonymy of S. lyra mainly depends, and this evidence has been wrongly interpreted. Hamon (1952) has shown that there is no second generation of hooks (the 'secondary' hooks of Ritter-Zahony) in S. lyra, but that in sexually mature specimens the existing hooks become ' claw '- shaped. She has suggested that this type of hook is a secondary sexual character. In S. gazellae a claw-type hook is found in the specimens at stages III, IV and V of maturity, but the claw shape is not nearly so pronounced as in S. lyra. There is no sign of a ' claw' in the inner margin of the hook, but only in the thin plate at the base, whereas both the inner margin and the base are 'clawed' in S. lyra. Comparison of Fig. $a-c demonstrates this point. The typical claw-type hook of S. lyra is characteristic and remains a useful feature in differentiating the species from S. gazellae.
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