i 9 o2] Collins, — Marine Cladophoras of New England 117 



1 

 felt's description of Sponogomorpha Hystrix or with Kiitzing's of 

 Cladophora Sonderi. Strdmfelt's plant, however, appears to differ 

 from ours merely in being more luxuriant, the filaments reaching a 

 diameter of 225 /* in the lower part, 360 p in the upper part, with 

 cell lengths in proportion ; the only other character mentioned is that 

 the filaments are often variegated by empty cells alternated with the 

 normal ones. This is hardly a definite character, but is likely to 

 occur from external causes. The variegated character is not notice- 

 able in a specimen of Rosenvinge, from Godthaab, Greenland, No. 

 162, which in all other respects agrees perfectly with Strdmfelt's 

 description. 



As regards C. Sonderi, the case is not quite so clear; the original 

 description in the Phycologia Germanica reads " Aeste gleichhoch, an 

 der Spitze ^-j^'", unten bis j^" dick ; Glieder meist so lang als 

 das Durchmesser, unten bisweilen doppelt langer, oben oft halb so 

 lang." This would indicate that the filaments were twice as large 

 in the basal part as at the tip, but the figure of Spongomorpha Sonderi 

 in the Tabulae Phycologicae shows no such distinction, the upper 

 part being a trifle larger, but only a trifle. If the original descrip- 

 tion is correct, the species does not belong in Spongomorpha at all: 

 if the plate is correct, it would seem that Kiitzing's name should be 

 retained. I have not been able to examine an authentic specimen, 

 but I have received from Reinbold a specimen from Helgoland, the 

 original locality, which he has marked C. Sonderi; it has short joints 

 and filaments largest at the tip, but the size of the filaments is less 

 than in the American plant, thus approaching C. arcta. 



The largest dimensions are found in specimens from the extreme 

 north, Greenland and Iceland ; it may be best to consider it as an 

 arctic species, diminishing in size as it ranges south, and at Helgo- 

 land, its extreme southern limit as to conditions though not in latitude, 

 only slightly exceeding C. arcta. The latter species has a wider 

 range, plants growing in Greenland and Iceland being practically 

 identical in character and size with plants from the English Channel 

 or from Long Island Sound. That the typical C. arcta is found at 

 Iceland in company with but distinct from C. Hystrix, speaks 

 strongly for their being distinct species. 



C. spinescens Ktitz. 



Kiitzing, Species Algarum, p. 418. 



C. arcta var. centralis Collins, Holden & Setchell, Phyc. Bor.-Am., 

 No. 721. 



Spongomorpha spinescens Ktitzing, Tab. Phyc, Vol. IV, p. 16, PL 

 LXXVIII. 



Main filaments about 80 fx., cells £-1 diam., growing tips up to 100 

 (x diam., cells 2 diam. long. Branches either erect and somewhat 

 clavate, or patent and acute ; branches of the latter type either short 

 and spine-like or long, hooked, revolute or even circinate. The 



