NOTES AND MEMOKANDA. 621 



more like the former ; but in the early stages the pole- dab appears 

 also to have a relatively large month, so that altogether personal 

 opinion has too much to do with the question. 



It must remain unsettled for the present whether the pole-dab 

 between 6 mm. and 12 to 14 mm. develops so slowly as to be but 

 little further advanced on its early condition, and is able also to take 

 on characteristics which are very like those of the young long- 

 rough dab. It is not impossible, because the further out to sea the 

 pleuronectids pass their lives, from larva to adult, the more prolonged 

 is their metamorphosis, and the pole-dab* has been obtained at greater 

 depths than the halibut.f 



Zeugopterus punctatus, Bl. (Miiller's Topknot). 



During February, 1901, a young topknot was obtained in a rock-pool 

 at St. Andrews, and as it showed an interesting stage in the develop- 

 ment of the scales, Professor Mcintosh kindly asked me to write a 

 short note on it. The total length of the specimen is 36 mm., and 

 greatest breadth without fins 15-5 mm. It is thus not quite so broad, 

 relatively to the length, as in the adult. The head, measured along the 

 side, is more than 30 per cent, of the total length, therefore greater in 

 proportion than it is later. These results are in accord with the now 

 well-known observations that as a fish grows its breadth increases and 

 head diminishes relatively to the length. 



The fin-formul£e are — 



D, 95 ; A, 70 ; V, 6/6 ; P, 8/10. 

 It is therefore a little abnormal in the pectoral of the eyed side, having 

 only 8 rays where usually there are 11 to 12. The ventrals are well- 

 developed, and are now joined to the anal. According to Sraitt 

 (Scandinavian Fishes, p. 456), they are separated from the anal at an 

 earlier stage. The colour and markings on the eyed side are as in 

 adult specimens, the blind side being quite colourless. The lateral line 

 is complete on the former side, but on the latter the arch over the 

 pectoral region is not yet formed. There is no trace of " otocystic 

 spines " on the eyed side, nor on the blind side. 



The greatest peculiarity, however, is that the scales are still in an 

 early stage of development. On the blind side, which in the adult 

 has only cycloid scales, none can be detected, and on the eyed side the 

 surface of the body and head seems covered over by numerous small 

 soft papilla?. When a scale is examined under a high power, it is seen 

 that these papilla are due to a pigmented epidermal fold which covers 



* Goode and Bean, Oceanic Ichthyology, 1896, p. 434. 



t I am indebted to Mr. E. W. L. Holt for tlie doubt with regard to these specimens. 

 At first I was disposed to regard them definitely as young halibut, but from a drawing 

 sent to him Mr. Holt is inclined to think them the pole-dab. 



