15 -A CONTRIBUTION TO OUR KNOWLEDGE OF THE MORPHOLOGY OF 
LAMELLIBRANCHIATE MOLLUSKS.* 
BY JAMES L. KELLOGG, PH. D. 
At the direction of Hon. Marshall McDonald, IJ. S. Commissioner of Fish and 
Fisheries, I undertook the following work at the Fish Commission station, Woods 
Holl, Massachusetts, during the summer of 1891, and while there enjoyed the kindly 
interest of that gentleman, as well as many attentions shown me by Dr. H. Y. Wilson, 
then biologist in charge. I am also much indebted to Dr. E. A. Andrews, of Johns 
Hopkins University, for aid and advice. I wish to express my appreciation of the 
attention and counsel given me by Prof. W. K. Brooks while engaged in this work. 
Before I began the work it was pointed out to me by Prof. Brooks, of Johns Hop- 
kins University, that the study of lamellibranch anatomy had been carried on almost 
entirely by means of dissections, which are difficult to figure or describe satisfactorily, 
and that comparatively little use had been made of sections. I hope to show not only 
that the anatomy of a single form may be easily described by this method, but that 
the comparative anatomy of various forms may be readily demonstrated. 
It is interesting to notice, in connection with this use of sections, that the great • 
amount of labor required in producing such a work as Deshayes’ Atlas, Mollusques, 
has been of little service. It is a very large volume of beautiful plates representing 
dissections ; but, even if they had been properly described, the comparison of special 
organs of different forms would have been very hard to understand. The cost of such 
a work also renders it inaccessible. 
Unfortunately I have been able to obtain but very few representatives of this 
group of mollusks for examination, and consequently do not feel able to attempt very 
wide generalizations. Since the completion of the present work a full and valuable 
paper by Prof. Paul Pelseneer (Ho. 17) has appeared, dealing principally with forms 
other than those here discussed. Much has yet to be done in comparative studies in 
this group, notwithstanding the great works of Lacaze-Dutliiers and others. 
* The principal species of marine bivalve or lamellibranchiate mollusks treated of in the present 
paper, which the writer has examined personally, are eleven in number, including six forms of greater 
or less economic value. The structure of other marine species and of the fresh- water mussels Unio 
and Anodon is also discussed. The eleven species first referred to are as follows : Mya arenaria Linn6 
(common long clam) ; Mactra solidissima Chemnitz (sea clam) ; Venus mercenaria Linn6 (quahog) ; Ven- 
ericardia borealis Conrad; Solenomya velum Say; Yoldia limatula Say; Area ( Argina ) pexata Gray; 
Mytilus edulis Linn6 (common mussel); Pecten irradians Lamarck (scallop); Anomia simplex Verrill; 
Ostrea virginiana Lister (oyster). 
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