110 



BULLETIN OF THE BUREAU OF FISHERIES 



floods, however, which raise the water to as high as 8 feet and widen the stream pro- 

 portionately; and as its bed is of coarse sand, it has become eroded to such an extent 

 that at ordinary times the water flows in a relatively thin sheet, in consequence of 

 which it becomes very warm and, no doubt, very well aerated also. 



The stream was muddy when visited. It is unshaded, except at rare intervals 

 when it approaches the banks. The current in the straight stretches is too swift 

 to be inhabited by many fish, but at fairly frequent intervals, where bends occur or 

 where a tree lies in the stream, an eddy may be formed; and in such places fish 

 usually were present, probably lying in wait for food brought down by the current. 

 Perennials are almost entirely absent along the banks of this stream, and none were 

 found growing directly in the water. 



MISCELLANEOUS COLLECTING PLACES 



In addition to the foregoing, a number of other places were visited but are not 

 deemed of sufficient importance to be taken up separately, either for the reason that 

 they do not represent types different from those already described or because 

 collecting in them was not practicable with the means at hand. 



1. Polyodon spat hula (Walbaum) 

 Spoon-bill cat; Paddle fish 



Sgualus spathula Walbaum, Artedi Piscium, 1792, p. 522. 



The unusual and even grotesque appearance of this strange fish is such that when once seen 

 it is easily remembered, as it differs widely from all other fresh-water species. It resembles the 

 sharks in several particulars and was classed with these forms by an early writer. This resemblance 

 is due to the absence of scales, the unequally developed caudal, the high dorsal fin, and perhaps, 

 also, to the form and position of the mouth, which superficially simulates that of the shark. Its 

 most distinguishing feature, however, is the extended spatulate snout, which is approximately one- 

 third of the length of the entire fish and is one-fourth as broad as it is long in specimens about 370 

 millimeters in length. It decreases in proportionate length with age. 



The paddle fish occupies a separate category from the other fish composing this collection, 

 as this primitive form does not develop the bony skeleton; but instead, the supporting structures 

 are of cartilage. 



Although of considerable commercial value locally during the winter, the paddle fish is not 

 taken frequently during the remainder of the year, and only four apparently landlocked fish were 

 obtained — three from a slough at Money and one from a lagoon near Lake Mclntire. These 

 approximated 680 millimeters (27 inches) in total length. 



The condition of the gonads of these paddle fish (taken in early July) showed the sex elements 

 to be far from mature. Virtually no information is available concerning its spawning habits. The 

 smallest paddle fish recorded (as far as known to the authors) had attained a length of over 4 inches. 



Examination of four stomachs indicates that only minute, free-swimming animal life, with 

 little vegetation, had been ingested; and as sand and mud were entirely absent, it is probable that 

 the paddle fish makes good use of its highly developed gills in straining this material from the 

 water as it swims about; and it is presumable that the produced snout has its principal use as a 

 sensory organ of value in determining the immediate presence of food, as it is traversed by two 

 well-developed nerve tracts, one on each side of the heavy central cartilage, and its entire surface 

 is sprinkled with sensory pits. The form of this organ is such that it would be well adapted to 

 stirring over the detritus. The small eyes, unless of unusual power, are of slight use in locating 

 the minute creatures fed upon, as most of them are almost transparent and in the muddy waters 

 sometimes frequented by the paddle fish would be virtually invisible. Although it is an awkward 

 fish and might appear poorly equipped to compete with other forms, it is essentially a specialist, 

 in that it makes use of the animal plankton, which is largely neglected by the other mature species 



