96 THE NAUTILUS. 



204. Modiolus (Branchydontes) hamatut Say, 1812. 



Mytilus hamatut Say, De Kay; Mytilut serratus Barnes, 1823; 

 Modiola hamatus H. F. Carpenter, 1865, A. E. Verrill, 1872 ; Brachy- 

 dontes hamatut Perkins, 1869. 



Thomas Say describes this species in the Jour. Acad. Nat. Sci., ii, 

 p. 257, 1822, under the name of Mytilus hamatus, giving for its local- 

 ity the Gulf of Mexico ; the specimens he described were obtained 

 from the markets of New Orleans, adhering to the shells of the south- 

 ern oyster, Ostrea virginica. Since his time it has been found on 

 oysters along the coasts of all the southern Atlantic States. Shell 

 very much contracted and incurved at the beaks, which are acute ; 

 surface covered all over with elevated radiating lines, which near the 

 umbos are divided into two and sometimes three ; color black or 

 very dark brown ; interior purple with white margins. Length two 

 and one-half inches, breadth one and a half, but sometimes as broad 

 as long ; very variable. 



Gould's Invertebrata of Massachusetts, 1840, does not mention 

 this species at all; even Binney's Gould, second edition, 1870, sup- 

 posed to contain descriptions of all the marine species inhabiting the 

 coast of Massachusetts, has not a word to say about it. It is, how- 

 ever, getting to be quite common in Rhode Island waters, but the 

 collector will obtain more specimens in five minutes in the oyster 

 markets of Providence, than he could collect at the shore in a week. 

 The first specimens I ever saw were given me by Mr. E. H. Jenks, 

 who obtained them in a fish market in Pawtucket ; neither of us 

 knew what they w r ere at the time, but I pronounced them to be 

 Modiolus at once. After carrying them home I referred to a vol- 

 ume of Say in my possession and saw by the figure and description 

 given in it that they were Mytilus hamatus Say. They were attached 

 to oyster shells. On seeing Mr. Jenks a few days after, I told him 

 what they were, but added, " they are not Mytilus if Say does say 

 so, they are Modiolus just the same." Since then the species has 

 become domesticated in our bay, having been brought here alive on 

 the southern oysters and transplanted in these waters. I have found 

 a few specimens in our bay not attached to oysters, stones or any- 

 thing else, but its proper habitat is on valves of Ostrea virginica, 

 adhering by a short, stout byssus. 



In November, 1870, Mr. Geo. H. Perkins published the " Mol- 

 luscan Fauna of New Haven," in which, speaking of this species, he 

 says, " An examination of the animal has led me to consider it a 

 Modiola rather than a Mytilus." He described it as a Modiola under 

 the sub-generic name of Brachydontes Sw., 1840. In 1872, Prof. A. 

 E. Verrill, in the March number of Silliman's Journal, p. 211, says, 

 Modiola hamatus = Mytilus hamatut Say. New Haven harbor and 

 vicinity, usually attached to oysters. 



