206 The Philippine Journal of Science 1923 



number in the mouth is not more than ten; the lower jaw often 

 has several pairs of large canines as an inner row near the 

 symphysis. The inner row on the maxillaries disappears with 

 age in most species, becoming a part of the outer row ; the teeth 

 are subject to great variation. 



Head compressed, with characteristically elevated occipital 

 region, due to the development of the powerful biting muscles; 

 anterior nostrils tubular, on top of snout; eyes small and cov- 

 ered with skin; cleft of mouth reaching behind eyes, often not 

 closing completely; origin of dorsal on head before or above 

 gill openings, which are small slits more or less horizontal or 

 circular. 



These morays are common throughout the warmer parts of 

 the Indo-Pacific and Atlantic Oceans and the Mediterranean Sea, 

 often literally swarming in the shallow water about rocks and 

 coral reefs, where some of the species attain a great size. Some 

 of them are among the most beautifully colored of fishes, with 

 rich and variegated hues and intricate, brilliant, often fantastic 

 patterns. They are among the most active of eels, many of 

 them greedy, bold fighters, striking like a snake at their prey. 



Many of them are highly variable, so that a great number of 

 nominal species have been described, based largely on color 

 variations or the changes due to age, as large old specimens 

 often diverge widely from the young not only in color but in 

 . dentition and proportions. Of the development of the young 

 nothing is known. The sands and pools of the coral reef flats 

 swarm with tiny mursenids, mostly Gymnothorax, whose specific 

 identity it is often impossible to determine. Like many other 

 families of tropical fishes, it will be impossible to be certain 

 of the morays until someone is able to study them in situ during 

 their life cycle. Many very unlike species bear an extraordi- 

 narily close resemblance to each other, while individuals of 

 the same species may have the most diverse appearance, even 

 when of the same size. 



Key to tl 



outside row. 

 P. Maxillary teeth ii 



f. Maxillary teeth in 



le Philippine species of Gymnothorax. 

 eeth on intermaxillary, conical, and not longer than 

 1 one row or in two rows in the very young, 

 two rows. G. thyrsoideus. 



