Diluvium of the Altmiht Valley, Bavaria. 331 
of the Spongillide of North America; unless it came from a 
statoblast like that represented by Dr. W. Dybowski (‘‘ Die 
Siisswasserschwiimme des russischen Reiches,’”’ Mém. Acad. 
St. Pétersbourg, tome xxx. no. 10, 1882, pl. i. fig. 4, a). 
With reference to the supposed identity of the spiniferous 
spicules in the diluvium of the valley of the Altmiihl river 
with those of S. ertnaceus, I would observe that having, 
through the kindness of Dr. Franz Vejdovski, of Prague, 
received on the 21st June last a copy of his valuable paper 
on the freshwater sponges of Bohemia (“ Die Siisswasser- 
schwimme Béhmens,” 1883), in which he has described and 
illustrated Spongilla erinaceus, Khr., under the ‘ subgeneric” 
name “Trochospongilla”’ (op. cit. p. 81, Separat-Abdruck), 
from specimens found at Celakowic and Podiebrad, on the 
Elbe, respectively about 13 and 26 miles H.N.E. of Prague, 
I wrote to him for a microscopic portion to examine, which 
he very kindly sent me on the 17th July following. 
I then saw in reality what I had previously only seen in 
print, viz. that strongly developed spiniferous character of the 
skeletal spicules which seems to have led to the specific term 
““erinaceus,” first used by Khrenberg as above stated; but 
still the spiniferous character generally, even here, was not 
nearly so much developed as in the smaller spicules of the Alt- 
mith! diluvium, although the dimensions and spznation too of 
the largest spicules were much the same. What, however, 
most struck me was the identity in form of the birotulates of 
Spongilla erinaceus with those of the American species 8. 
(Meyenia) Leidyi, Bk., so that I began to think that 
they must be the same species; however, I find that the 
skeletal spicules of Meyenia Lecdyi in the specimen described 
by Dr. Bowerbank and those lately sent me by Mr. Potts are 
smooth, almost cylindrical, and abruptly pointed, averaging 
in their largest size not more than half the length of those of 
S. ertnaceus from the Elbe, which, on the other hand, are 
fusiform and gradually pointed; thus a difference in this 
respect seemed to me to be evident ; but on going further and 
comparing the skeletal spicules of S. er?naceus with those in 
the jirst tragment sent me by Mr. Potts, viz. that mounted on 
a slide from the Schuylkill river, I find the two almost iden- 
tical. Now as the original specimen named by Dr. Bower- 
bank, which Prof. Leidy sent to him in 1863, came from the 
same river, it follows that the difference in the skeletal 
spicules to which I have just alluded goes for nothing, and 
therefore that the Kuropean and American species must be 
considered identical ; while the stelliform branched excretory 
canal-systems on the surface of the entire specimens latterly 
