OLDEN TIME KNOWLEDGE OF HIPPOCAMPUS. 



By Charles R. Eastman, 

 American Museum of Natural History, New York. 



[With 4 plates.] 



From time immemorial the interesting little fishes known as sea 

 horses (Hippocampids) have attracted attention on account of their 

 curious form and no less peculiar habits. Occurring plentifully in 

 the Mediterranean, the typical species {Hijypocampus hippocampus 

 or antiquorum) was well known to the ancients; and owing to the 

 wide distribution of the remaining thirty-odd species composing the 

 genus, sea horses have become familiar objects in most of the large 

 aquaria of the world. 



We owe to the late Dr. Theodore N. Gill an interesting account of 

 the life history of Hippocampines, published in volume 38 (1905) of 

 the Proceedings of the United States National Museum. More re- 

 cently a number of pictorial representations of the common Mediter- 

 ranean species, taken from old authors, have been reproduced in a 

 short popular article by Prof. R. C. Osburn (Zoological Bulletin, 

 March, 1915). 



The movements, feeding, and breeding habits of these creatures 

 are all extremely curious, and have been so well described by Dr. Gill 

 that we can not forbear quoting a few^ paragraphs from the article 

 referred to, before turning to the accounts given by two or three old 

 writers not mentioned by Prof. Osburn. 



Concerning the attitudes and movements of sea horses. Dr. Gill 

 remarks that the " the most frequent position is a state of rest, with 

 the tail wound around the stem of a plant or some other substance, 

 and the body carried nearly or quite erect." Continuing, this dis- 

 tinguished observer writes: 



Such is the most frequent position, but notwithstanding the apparent rigidity 

 of the cuirass almost every other attitude consistent with such a form may 

 be assumed. The body may be thx'own outward at various angles and even 

 downward and the tail wound around a plant in a double coil. Once in a 

 while one eye may roll toward you while another may be passive or look 

 backward or in an opposite direction. It becomes obvious that the little fish 

 can move its eyes independently of each other and in entirely different ways. 



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