8 DISCOVERY REPORTS 



on 26 December 1947 is therefore advanced as independent evidence supporting Bertelsen's 



conclusions : 



' When the fishing lure was removed for safe preservation I found it possible to withdraw the (basal) 



bone, without forcing, for a distance of 24 cm It extends back at least as far as the base of the dorsal 



tentacle, where it probably has its morphological origin (although an X-ray photograph* of this region 

 was taken, but revealed nothing) Is it possible that the rod can be pushed out and in, i.e. is ad- 

 justable for length? Certainly the rod, when half pulled from its insertion (on the head) and let go, 

 slowly moved back again.' 



The dorsal tentacle of the new specimen (PI. I) is a cylindrical structure, quite soft and flaccid when 

 fresh, and of a greyish black colour. The tip is slightly expanded. It measures 6 cm. and is raised upon 

 a distinct peduncle 1-2 cm. high. According to Bertelsen's conclusions, this tentacle should have in- 

 vaginated when the lure was pulled from its insertion. I cannot recollect this, but it may have happened 

 and been overlooked, the examination being hurried and the phenomenon unsuspected. Alternatively, 

 the proximal end of the rod may have become detached from the inside of the tentacle after death. 



...•Xv.*a$ 



*j&k 



ABC 



Fig. 2. Ceratias holbolli Kroyer. The caruncles. A, ' Mancalias tentaculatus', x 5. B, Antarctic specimen, x z\. 



C, Regan's specimen, x it. 



In Regan's specimen the cephalic tentacle is absent and he notes ' that the dorsal tentacle is long, 

 reaching beyond the base of the caudal fin, when laid back, and bears a terminal bulb' (Regan, 1926, 

 p. 34). He considered this was either the normal structure of the dorsal ray, or an assumption of the 

 structure and function of the cephalic tentacle caused by loss of this tentacle during life (Regan, 19250). 

 I have re-examined this long dorsal ray, which emerges from the torn base of the former integument 

 of the tentacle (Fig. 2C). It is spirit material, and appears inelastic and much shrivelled. Probably it 

 represents a part of the pterigiophor prolonged by remnants of its musculature ; the ' terminal bulb ' 

 seems to be a bunched knob of connective tissues. There is little doubt that these damaged structures 

 correspond to the dorsal tentacle of the Antarctic specimen. 



The musculature of the cephalic tentacle of the Ceratioids has been studied in Gigantactis by Brauer 

 (1908) and Waterman (1948), and in Ceratias by Rauther (1941) and Bertelsen (1943). Brauer could 

 find only four pairs of muscles associated with the structure. Both Bertelsen and Waterman have 

 recorded five pairs, which can be homologised in the two genera. Two of these muscles are the retractors 

 and exsertors of the basal bone. They are elongate and weak in Gigantactis where fore-and-aft adjust- 

 ability of the lure is not specially developed. On the other hand, in Ceratias they are elongate, but also 

 large and powerful, and are the principal effectors of the mechanism already described. A third pair of 

 muscles are attached to the basal bone. They are powerful in Gigantactis, where Waterman describes 

 them as the inclinators of the illicium. They are small and weak in Ceratias, where they may also, as 



* By the ship's surgeon, Dr Michael Gilkes, to whom I am indebted. Probably the hardness of the X-rays employed accounted 

 for the failure. 



