62 PROCEEDINGS OE THE ACADEMY OF 



clay (old aestuary) deposit immediately underlying it. Among these a few of the 

 most common are, Eupodiscus R a lfs i i, E. argus, Coscinodiscus gigas, 

 C. ocul-iridis, C. centralis, Triceratium s t riol atum, T. punc t a- 

 tum, Actiniscus sirius, &c, Sceptroneis caduceus, occurs living on 

 algae at Riviere du Loup, St. Lawrence river, Goniothecium obtusum at 

 Black Rock Harbor, L. I. 



The important question, too, of the influence of locality on the growth and 

 development of species no where presents itself in so interesting a point of 

 view as in this country. The large extent of its sea board, embracing every 

 variety of climate, the continuous chains of sestuaries and sounds along the 

 entire line of coast, and the many rivers, large and small, traversing every kind 

 of soil from the southern alluvial to the granite ranges of the north east, offer 

 an unsurpassed field for the study of this influence. 



Although not able to pursue the subject at this time, I cannot refrain from 

 alluding to a fact which forces itself on the mind at an early stage of these in- 

 vestigations, viz.: the great distance from the sea at which marine influences 

 continue to make themselves felt. Philadelphia is situated nearly a hundred 

 miles from the ocean, and even at the period of spring tides at least fifteen 

 miles above the faintest suspicion of brackish water, and yet quite a number 

 of the diatoms in the Delaware at this point are pm - ely marine, and a still 

 larger number brackish. The agency of migratory fish, as the shad and low 

 swimming sturgeon, in bringing about this result, is no doubt important, but 

 will not serve to explain the presence of brackish and marine species in the 

 ditches adjoining Cooper's Creek, a tributary of the Delaware, and in Fox Chase 

 Run, some ten miles above this city, at points not within tidal range. The 

 old asstuary bed of the Delaware (blue clay) before alluded to, was very rich 

 in these forms, and by digging down a short distance at any part of the meadow 

 land bordering the river, the blue clay which contains them may be exposed. 

 An idea which naturally suggests itself under these circumstances as a solu- 

 tion of this paradoxical difficulty is, that possibly the telluric impression of 

 the subjacent soil may continue to make itself felt in the development of spe- 

 cies for a long period after the other surroundings have ceased to be favorable. 



At all events it needs some other explanation than that ordinarily had re- 

 course to viz. the hardihood of these low forms of organic life, and the agency 

 of birds and fish to account for the permanent localization of marine species at 

 points apparently so unsuited to their existence. 



I. New species and Sporangial forms. 



1. Triceratium alternans, Bailey. Sporangial ? This somewhat doubtful 

 form has so few of the characters of T. alternans, that but for the occur- 

 rence of intermediate varieties the propriety of its reference to that species 

 might seem questionable. The structure of the valve is distinctly cellular, in 

 the smaller varieties indistinctly so, and that of the obtuse processes faintly 

 punctate. The largest pustules attain the size of T. fa v u s. 



Hab. St. Mary's river, Ga. , in scum of a salt marsh. 



2. Surirella pulchra, n sp. F. V. Linear narrow, often somewhat twisted. 

 V. Ovate or elliptical, alse distinct, canaliculi numerous, marginal inflated as 

 in S. fastuos a, 6 in '001, extending for about two-fifths of the distance to 

 centre of valve, central portion smooth circumscribed on either side by a 

 coarsely striated arcuate band with harshly defined edges, and connected with 

 its fellow at a short distance from the end of the valve. Immediately exterior 

 to these bands, and separating them from the inner termination of the canali- 

 culi throughout the entire length of the valve, is a corresponding only some- 

 what narrower arcuate smooth space. Length of valve *005 to "009. PI. I. f 1. 



This very beautiful form, evidently allied to S. f a s t u o s a and S. e x i m i a, 

 Mic. Journ., differs from both in the greater number of its canaliculi and the 

 presence of the striated bands. In this respect it closely resembles the species 

 next to be described. 



[March 



5 



