ACEPHALA. 11 
N. minuta, Gould, 101. (non O. Fab.) — Corall. East- 
port Harb. in 6 f., also off Grand Manan in 40 f. 
(W.S.) Off Isles of Shoals in 20 f.(Wh.)  Prov- 
incetown Harb. (Tott.) 
MY TILIDA. 
After an examination of the animals of our species 
of this family, I have arrived at the conclusion that 
the genera Modiola, Crenella, Modiolaria, etc., should 
be reunited to Mytilus, since I have found as great 
differences between the species of these subgenera as 
among the subgenera themselves. In the last edi- 
tion of the “ Régne Animal,” the eggs of Mytilus are 
said to be found in the mantle. In an examination 
of several individuals of M. edulis by Dr. Burnett 
and myself, we found the glands of the mantle filled 
with spermatozoa. The spermatiferous glands are 
arranged differently in different species. In M. dis- 
cors they present a beautiful dendritic appearance, 
occupying nearly the whole extent of the mantle. In 
some species they appear to occupy only that portion 
of the mantle which is united with the abdominal 
mass. 
Myrinus pecussatus, Mont. Modiola glandula, 'Tott. 
Gould, 131, f. 87. Crenella decussata, Dekay. F’. et H. 
—Laminarian. Whole Coast. Eastport in 4 to 40 f. 
sandy mud, (W. 8.) Off Isles of Shoals, 20 f. sand 
(Wh.) Provincetown at low water, (Low.) Ston- 
ington, (Linsley,) and at intermediate points. 
M. pectinuuus, St. Modiola pectinula, Gould, 127, f. 85. 
