GENERAL REPORT ON INVESTIGATIONS IN PORTO RICO. 
15 
largely of mud, in places overgrown with grass. It is navigable for rowboats for a 
mile or more above its mouth. 
Rio Luquillo. — This stream has its sources on the slopes of El Yunque Mountain 
and flows northward, entering the sea near the village of Luquillo. Different 
branches of this river were examined at various places on and about El Yunque, 
where they are all swift, turbulent mountain streams, full of falls, cascades, rapids, 
and small but relatively deep pools. The bed is usually of rock and is well covered 
with bowlders of various sizes. The water was always clear and pure and the maxi- 
mum temperature February 19 was 69°. There was but little aquatic vegetation 
visible, but small crustaceans ( Atya scabra and Xiphocaris elongata) were quite 
common. These streams are doubtless not materially different from other mountain 
streams of this island, particularly those having their sources in dense shade, such 
as prevails upon the slopes of El Y unque. Although the amount of water is not 
great, and there are no long, quiet reaches, there is ordinarily a continuous stream of 
sufficient volume to permit fishes to pass easily throughout the entire length, barring 
the impassable falls. The deep pools are often of good size. The relatively low tem- 
perature and the character of the water, together with the presence of crustaceans, 
which would afford a food supply to a limited number of fish, render it probable that 
the small-mouthed black bass might be introduced into these streams with a fair pros- 
pect of becoming established. Indeed, a maximum temperature of 69° would not be 
unfavorable to the rainbow trout, which we have seen in southern California in small 
streams very similar to those examined on El Yunque, and whose summer temperature 
is probably no lower. The experiment of planting the rainbow trout in some of these 
Porto Rican streams and the small-mouthed black bass in others is well worth trying. 
Lagoons of Porto Rico. — There are no real lakes on this island, but near the shore 
are several lagoons. These are usually narrow and relatively long, separated from 
the sea by a low, narrow strip of sand and surrounded by a dense fringe of man- 
grove bushes, which makes it difficult to reach them. Some of them have permanent 
connection with the sea, while others are connected oidy during times of heavy rain. 
The water in most of them is strongly brackish or salt, while in a few it is relatively 
fresh. The fishes frequenting these lagoons are chiefly mullets and snooks (“liza” 
and “robalo”). The principal lagoons are Tortuguero and Cana Tiburones near 
Barceloneta, and Guanica and Flamencos near Guanica. 
LOCAL INVESTIGATIONS. 
When the Fish Hawk was assigned to the Porto Rican investigations, it was 
understood that she would have to return to the United States early in the spring to 
engage in shad-hatching operations on the North Carolina coast. In order, therefore, 
to accomplish as much as possible, it was arranged to carry on synchronously four 
lines of work whenever possible. 
1. A party usually consisting of Professor Evermann and Mr. Wilson, assisted 
by four to six men of the ship’s crew, with the steam launch, a flatboat, seines, and 
other apparatus, would do collecting along the shore, particularly in those places 
where seining could be done. 
2. Another party under Mr. Marsh (sometimes assisted by Mr. Wilson) and 
four to six sailors using the oil launch would do collecting on the reefs, paying par- 
ticular attention to the invertebrates. 
