142 THE AMERICAN MONTHLY [May, 



From what has been said, it may readily be seen that if M. 

 Tempei-e had examined more samples, from other parts, and 

 strata of the deposit, the above list would have been greatly ex- 

 tended. Navicula per magna and N. maculata are not men- 

 tioned, but they occur in extraordinary abundance, the latter in 

 several very fine types in parts of the deposit. Actinocyclns 

 harkleyi^ A. ralfsii, A. ehrenberguTxwA A. crassus ■a.re recognized 

 in the Connecticut shore diatoms. Of these A. barkleyi is by 

 far the most abundant. The pseudo-nodule, so easily seen in A. 

 ehrenbergii and in A. crassus and generally in A. ralfsii, ap- 

 pears to be absent in the majority of valves of A. barkleyi. Al- 

 though this is one of the heaviest of diatoms and appears so dense 

 when mounted in balasm, valves which have never been dried 

 are so transparent in water that their markings can scarcely be 

 seen. This shows some peculiarity of structure in which they 

 difler from other diatoms. I have lately found A. barkleyi of 

 presisely similar type to that of the Connecticut shore in material 

 sent me from distant localities. 



Dr. Edwards sends earth from different localities on the New 

 Jersey shore which contains the same Actinocychis^ and mud 

 from a swamp in Melbourne, Australia, has the same associated 

 with Navicula cancellata and Hyalodiscus siibtilis and H. 

 radiatus. On the Connecticut shore, N. cancellata occurs 

 abundantly in tide pools in the marshes with P. balticuin^ and 

 Hyalodiscus is found in deeper and more saline waters. 



In Cunningham's find in a marsh near Mobile river is the 

 same Actinocyclus again, with remarkable specimens of Terp- 

 since musica, which occurs only sparingly on the Connecticut 

 shore. Soundings from near Cuxhaven, North Sea, contain Ac- 

 tinocyclus ehrenbergii and A. crassus., with abundant Eupo- 

 discus argus and Triceratium favus and an occasional Na- 

 vicula maculata, precisely similar to those of New Jersey and to 

 the smaller type from Leete's Island. 



I find in the Morris creek material Actinocyclus tentiissimus 

 and Actiitoptychus subtilis (Van Heurck's Diatoms of Bel- 

 gium, plate cxxiv, fig. 7, and plate cxxv, figs. 3 and 3). I 

 find also a form larger than any of the others, which, instead of 

 the small marginal spines, has elevated ridges extending about 

 one-third the distance to the centre of the valve, and which has 

 striation decidedly difterent from any other. Plate cxiv, fig. 9, 

 shows Triceratium brightwellii West, var. trigona {Ditylium 

 trigo7ium Baile}'), which I have found at Branford, Conn. Figs. 5 

 and 8, showing entire frustules. are imperfect, as the central spines 

 are broken. The Branford forms show longer spines terminating 

 in a knob or ball. 



Soundings from the oyster beds at Clinton, Conn., show nu- 

 merous minute varieties, many of which are rare. The larger 

 forms are chiefly varieties of Coscinodiscus and of other kinds 

 previously mentioned, with Pleurosigma balticzim., P. america- 



