466 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



ters are always planted, thus greatly modifying tlie natural conditions 

 of such localities and introducing a large number of species not prop- 

 erly belonging to the true muddy bottoms. 



The shores of the muddy estuaries and ponds, or lagoons, are usually 

 low, flat, and bordered by more or less extensive salt-marshes, with the 

 surface generally just above high-water mark of ordinary tides, but lia- 

 ble to inundation by unusually high tides. These marshes are always 

 traversed by winding and sluggish tidal streams of brackish water and 

 by smaller ditches, and the surface is often diversified by small pools or 

 ponds of impure brackish water, in which there is generally a deep de- 

 posit of soft, slimy mud and decaying organic matter, which often be- 

 comes putrid, and exhales fetid gases. All such waters, whether in the 

 ditches or pools, and however filthy they may be, are inhabited by cer- 

 tain kinds of invertebrate animals, and they are also frequented by mul- 

 titudes of minnows and other small fishes, which undoubtedly find 

 abundant food in such places. 



In these brackish pools and ditches we find certain beetles, both in the 

 adult and larval stages. Among these the most conspicuous is Hydro- 

 philus quadristriaius Horn., a large, black species, which appears to be 

 common. The larva of the salt-marsh musquito (Culex, sp.,) also lives in 

 such situations, and the adults in August, September, and October, so 

 swarm in these marshes as to render it extremely unpleasant to go on 

 or near them. The larva? of an Ephydra also occurs, and many other 

 insects will doubtless be found in these places when carefully sought for. 



One Amphipod, the Gammarus mucronatus, commonly lives in the most 

 brackish pools and among the grass on the marshes. The prawn, Palce- 

 monetes vulgaris, (Plate II, fig. 9,) is also very abundant in these pools 

 and ditches, even where the water is but little salt, and also occurs in 

 immense numbers on the muddy bottoms and among the eel-grass of the 

 estuaries. In the pools there are also myriads of small Entomostraca 

 of many kinds, upon which the prawn and other species feed, while the 

 Entomostraca find an abundance of ciliated Infusoria and other micro- 

 scopic animals for food. 



We find several species of crabs burrowing in muddy banks along the 

 shores of the estuaries, as well as along banks of the streams and ditches 

 in the salt-marshes. The most abundant of these is the marsh fiddler- 

 crab, Gelasimus pugnax, which is often so abundant that the banks are 

 completely honey-combed and undermined by them. These holes are of 

 various sizes up to about three-quarters of an inch in diameter, and de- 

 scend more or less perpendicularly, often to the depth of two feet or 

 more. Occasionally in summer these crabs will leave their holes and 

 scatter over the surface of the marshes, which at such times seem to be 

 perfectly alive with them, but when disturbed they will scamper away 

 in every direction and speedily retreat to their holes, but occasionally, 

 at least, they do not find their own, for sometimes the rightful owner 

 will be seen forcibly ejecting several intruders. It is probable that at 



