PALAEONTOLOGY: EASTERN MASSACHUSETTS. 53 



clayey texture than is the main mass ; and in this, and a little 

 distance above and below, all the fossils were found. The same 

 sands as below succeed this bed, capped by ordinary semi-strati- 

 fied pebbly drift. 

 The following partial list of fossils is given by Shaler : 



Leda. Two specimens. 



Modiola discrepans Say. Several. 



Mya truncata, Linn.? " 



Mesodesma arctata ? Very doubtful. 



Nucula sapotilla 1 



Panopea arctica Gould.? 



Saxicava distorta Say. 



Five or six specimens of lamellibranchiates, not identified. 



Crustacean remains plentiful but very fragmentary. 



4. BOSTON. 



(Undisturbed Recent fossiliferous beds.) 



Post-Pliocene fossils of very recent date have been obtained at 

 three localities in Boston ; at each of which they were, unlike the 

 drift shells, taken from the beds in which they were originally de- 

 posited. The fossils were brought to light by excavating ; and the 

 localities are now covered over so that at present no more spec- 

 imens can be obtained. The fossils were listed in several papers 

 by Upham, and the specimens may be seen now in the collec- 

 tions of the Boston Society of Natural History, or the Institute 

 of Technology. Some of the rarer species are in the possession 

 of one of the collectors, Mr. Warren Herman. 



A. Valley of Muddy river, Brookline district. — Here an ex- 

 cavation for a sewer exposed a fossiliferous clayey stratum, near 

 the present level of low tide. It is underlain by stratified clays, 

 and overlain by about one foot of peat, succeeded by five to 

 twelve feet of muddy alluvium. Thirteen species were found, 

 most of them molluscs now inhabiting this coast. 



B. North bank of Charles river at Cambridge end of Harvard 

 bridge. — Here all the land lying between the river and the rail- 

 road was built up from the dredgings taken fro m the bottom of 

 the river. Below the river mud, sands were met contain- 

 ing twelve species of fossils. These were brought up by the 

 dredge in vast numbers. The most abundant species were Ostrea 



