175 

 BIOLOGICAL & FAUNIRTIC NOTES ON TRINIDAD. 



Fkom the German by Dr. von Kennel. 



(Concluded.) 



4. "We now come to the large rivers of the plains. Their 

 fauna is more distinct than that of all the other forms of water. 

 The two large rivers in Trinidad are the Ciironi and the Ortoire ; 

 the former flows from East to West, and drains the Northern 

 range of hills, thy latter takes its origin in the Southern part of 

 the Island, draining the centre and deriving its waters from 

 small rivulets and swamps. Both these rivers are alike, in so 

 far that the current of their middle and lower course is not 

 strong, so that they rise and fall with the tide a considerable 

 distance from their deltas In the dry season the water is 

 brackish a long way up the course, but in the rainy season the 

 strength of the current prevents the sea forcing its way tip, so 

 that during that time the water is sweet its whole length. 

 The vegetation, of course, corresponds to this disposition ; at 

 the deltas true mangroves are found to about 1-1^ miles up the 

 course. The few animals 1 refer to in the following lines come 

 from the Ortoire and were captured about 8 miles from the 

 mouth, at a place where the difference of tides is about a foot 

 and a half, but where the water is not brackish. Large banks 

 of Mytilaceae of all ages were found on a steep bank which was 

 of a soft kind of stone, covered with mud. A decayed tree that 

 was partly in the water was also covered with these mussels to 

 high water mark. The animals are already conspicuous by 

 being found in sweet water, but it is also interesting to note the 

 heat of the sun they stand at low tide. The same remark 

 applies to a Fhola species, which lives among these mussels. 1 

 also captured an interesting Lmuhriconia at the same spot. A 

 crustajcean, belonging to the genus ^ga, was also an inhabitant 

 of the mussel colony, the occurrency of which in sweet water 

 was already made known by Proiessor Semper. The shallow places 

 near the banks were inhabited by a totally transparent Palae- 

 monide and a slightly colored Atya. We have to deal here with 

 a marine fauna in sweet water ; for even if the representatives 

 of the genus Atya. Palaemoiiidae and Mytiliceae are nearly all 

 sweet water inhabitants, they still belong to families which are 

 only found in the sea. 



On the East Coast of Trinidad so-called lagoons are particu- 

 larly interesting, 'ihey originate from the little rivulets which 

 drain the low hills during the rainy season and flow directly 

 into the sea. As soon as the dry season sets in, the water supply 



