238 PROCEEDINGS OF THE ACADEMY OF [1887. 



Ifeas. Skeleton spicules O'Olll by 0'00045 inches. Dermal spic- 

 ules 0-0025 by 0-0001 inches. Shaft of long birotiilates 0-0029 by 

 0-00015 inches; diameter of rotule 0-0009 inches. Length of short 

 birotulates 0-00168 inches ; diameter of its rotules O'OOOT inches. 



Sab. On plants, timber, etc., in shallow water. 



Loc. In the pool at Lehigh Gap, Pennsylvania ; in Lake Ho- 

 patcong, New Jersey, and at other places along the Eastern coast 

 of the United States. 



Lehigh Gap, frequently mentioned as a locality in these descrip- 

 tions, is a rail-road station and quiet watering place, Avhere the 

 Lehigh River forces its Avay through the Blue JNIts. in Carbon 

 County, Pennsylvania. The mountain chain or ridge, with an ele- 

 vation of about eleven hundred feet above the river, is here abruptly 

 cut through by it, leaving on one side precipitous, jagged edges of 

 bare rock ; Avliile on the other it more gradually slopes from the 

 river to the summit. 



Nearly at the narrowest point the river is crossed by an old time 

 suspension bridge depending from chains composed of long iron 

 links. On the bank of the river just below, there stands, or until 

 quite recently stood, the ruin of an old mill, that had been burned 

 before the memory of the oldest inhabitant. The mill race, passing 

 under an archway through its walls, was choked by the fallen and 

 blackened timbers, amongst which the water could hardly have 

 been said even to creep, excepting when a freshet in the adjacent 

 river supplied its fauna and flora with a momentary draught of 

 fresh Avater. 



It so chanced that during the early days of my enthusiasm for 

 sponge collecting, curiosity led me to look into this pool, in reality 

 little more than a very wet cellar, with the result of adding a new 

 genus {Heteromeyenia) to the system of fresh water sponges, with 

 two species pertaining to the same ; also a variety of Spongllla fra- 

 gilis, a form of Meyenia fluviatilis and a new species {T. penn- 

 sylvanicd) of the genus Tuhella, its first discovery in other waters 

 than those of the River Amazons, South America. Numerous spec- 

 imens of the higher types of minute aquatic life; fine species of 

 Brijozoa etc., gave added interest to this field of work. 



On October 13th., 1880 the first specimen of H. repens was dis- 

 covered upon the stems and leaves of a Potamogeton, by my friend 

 and companion Mr. J. S. Cheyney ; and after reaching home I found 

 that I had, myself, collected others from the fallen timbers, without 



