930 The American Naturalist. [November, 
ing a thickened body in the middle with a tapering filament 
given off from either end of it. The only difference between 
the two ends of the central body of the sperm-cell was the pres- 
ence of the nucleus at one end from which the longer filament 
was given off. During life, both of these filaments are spirally 
but loosely coiled about one another, and during progressive 
motion this arrangement gives rise to. the appearance of a vi- 
bratile membrane spirally placed on the tail. On adding 
Perenyi’s fluid to the sperm, the cells, one and all, flew out 
straight and rigid, and the refractive body (nucleus ?) became 
very distinct in each. I have observed this structure in other 
fish spermatozoa, but never so distinctly marked as in the cow- 
nosed skate. It is possible that the double tail of Protopterus 
will be found to be constructed after this plan. 
Owing to the very great scarcity of specimens of Lepidosiren 
paradoxa, it may be of interest to many to have a list of the 
known examples with their present resting places. 
The following is a table of all the South American speci- 
mens of Lepidosiren yet taken and recorded : 
Specimen ae Locality. Size. Condition. Museum. 
No. 1 Natterer | Borba on the R. Madeira, | 
1836. 3ft.9 in. | Dissected |- Vienna 
No. 2 Na terer Villa Nova onthe R. Ma- 
E 1836. 1 ft. 10 in. Dissected | Vienna 
No. 3 | Unknown j|Unknown, 1840. Paris 
No. 4 Castelnau qune boa 1847. Dissected Paris 
Dr J. Barbosa, | Igrapé de Aterro, (Ma- Florence, 
No 51 Rodriguez | f náos), 1886. pa Sen, Go, fetale Wane | py 
No. 6 Rodriguez |Autaz, Madeira River,'87| inem. 40 Whole | Florence, 
Italy. 
The fifth specimen was a female with well-developed eggs, 
which was caught in August, 1886. It was 85 em. in length, 
and 28 cm. in girth at thep ien appendages. she one is 
distinctly cylindrical in shape, b nth 
dominal surface where the scales are bigger, thicker and lighter 
incolor. The tail is short and much compressed, and is provided 
with an irregularly-rounded caudal fin, which is not continued 
cephalad as a true median fin, but only as a slight keel to the 
middle of the back. The fin rays of the caudal portion are 
