36 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Wood's Holl. Common on Zostera. Summer. 



From Harvey's description, it would be.difficult to recognize this species. From 

 an authentic specimen in our possession, collected by Harvey at Pecouic Bay, the 

 filaments are seen to be from .0095 mm to .01115 mm in diameter. The sheaths are dis- 

 tinct, but less marked than in L. cesluarii, from which the present species differs in 

 the shortness and smaller diameter of the filaments, and in the color, which is a dark 

 purple, at times almost black. The filaments differ from those of both L. majuscula 

 and L. cestuarii in being held together by an amorphous, gelatinous substance, sup- 

 posed to be characteristic of the genus Phormidium. That genus, however, includes 

 plants which are now properly assigned to other genera. 



We have often searched for this alga, but have never found a form which seemed 

 to correspond exactly to Harvey's specimen. The same alga has, however, been col- 

 lected by Mrs. Davis at Gloucester. At Wood's Holl is a Lyngbya, distributed iu 

 Alg. Am. Bor._ Farlow, Anderson & Eaton, No. 47, which is not uncommon, forming 

 patches several inches long on Zostera, and which resembles L. nigrescens closely in 

 everything but the greater diameter of the filaments. Its sliminess and the delicacy 

 of the filaments cause it at first sight to be.mistaken for diatomes. In drying, it be- 

 comes somewhat greenish. This species, which resembles closely L. Kutzingiana, 

 Thuret (Phormidium, Le Jolis), we can regard only as a large variety of Harvey's L. 

 nigrescens. 



CALOTHBJX, (Ag.) Thuret. 



(From aaloc, beautiful, and -&pti, hah'. ) 



Filaments terminating in a hyaline hair, fixed at the base, free above, 

 occasionally branching, growing in little tufts or strata of indefinite ex- 

 tent, heterocysts present in most of the species, no oscillations. Spores 

 unknown. 



We adopt the genus with Thuret's limitations, includiug, iu part, the genera Schizo- 

 svplion, Amphithrix, Leibleinia, &c, of Kiitziug. 



a. Species growing in little tufts. 



C. confervicola, Ag. [Leibleinia clialybea and amethystea, Kiitz. — 

 C. confervicola, Ag., Phyc. Brit., PI. 254; Notes Algologiques, PI. 3.) 

 PI. I, Fig. 6. 



Tufts fasciculate, filaments dark bluish purple, attenuated, .018 mm in 

 diameter, heterocysts all basal, generally few in number. 



On algoe of all kinds. Summer. Very common. Europe. 



C. Crustacea, (Schousb.) Born. & Thur. (Sehizosijrfion fasciculatus 

 and lasiopus, Ktitz. — Oscillatoria Crustacea, Schousb. — Calothrix Crus- 

 tacea, Bornet & Thuret, Notes Algologiques, \). 13, PI. IV.) 



Tufts fasciculate, filaments bright green, attenuated, .0125 mm in diam- 

 eter, heterocysts intercalary, often very numerous. 



Exs. — Alg. Am. Bor., Farlow, Anderson & Eaton, No. 49. 



On algse of all kinds, and on rocks. Summer. Very common. Europe. 



The two species just described are very common, certainly from Wood's Holl to 

 New York, and probably also northward, on all kinds of algse, on which they form 

 fine tufts or fringes. The two species usually grow mixed together, but may be 



