OF NEW SOUTH WALES. 245 



tinge on the sides of the head, leaving a large oblong white spot 

 on the posterior part of the head, which extends to the rest of 

 the pectorals. 



From Moreton Bay. The specimen is nearly sixteen inches 

 long. 



Note. — This species resembles Ophisurus alternans, Quoy and 

 Gaim. Yoy. Freycinet Zoology, pi. 45, fig. 2. 



Triacanthus biaculeatus. 

 Triacanthus biaculeatus, Block, p. 148, fig. 2. 



A specimen about four inches long of this curious fish was 

 sent to me from Cardwell, in the north of Queensland. It is 

 entirely of a silvery colour ; the anterior profile of the head is 

 more elevated than Block's figure. 



This sort inhabits the Indian Archipelago, and Dr. Gunther 

 quotes it from Port Essington. We see that it follows also the 

 North East Coast of Australia. 



MONACANTHUS YAGOI. 



It is always with much reluctance that I describe a species 

 of this genus as new, for it is stated that they are subject to 

 great variations during their life. This is rendered probable by 

 the fact that it is very rare that I can place the specimens I 

 obtain under any of the species described by the authors, and it 

 would be very desirable that large numbers of specimens were 

 studied to well establish their specific differences. Unfortunately 

 the Australian fishermen not only cannot be induced to collect 

 them, but always throw away any Leather Jackets that they may 

 get by chance. They are very rarely caught with the net, and 

 they only take the hook with difficulty. They also generally 

 inhabit the vicinity of rocks where the fishermen do not willingly 

 carry their researches. The present sort is in form, nearly allied 

 to Monacanthus variabilis of Richardson, but its anterior profile 

 is much more convex ; the mouth is not protruded ; the dorsal 

 spine is straight and is inserted over the centre of the orbit ; the 

 body is velvety ; the centre of the tail is covered with short stiff 

 slender spines, and behind these are two tubercular arms with 



