476 BULLETIN OF THE BUREAU OF FISHERIES. 



This species varies considerably in the size of the clusters, the height of the upright branches, the 

 amount of branching, and the amount of flattening. The clusters may be dense or loose, the upright 

 branches may be 2 to 7 cm. tall; branching is usually sparse and irregular, but may be fairly regularly 

 pinnate at the apices, or the fronds may be entirely unbranched; they are usually almost terete, but 

 may show slight, distinct flattening. 



The two species occurring in this region can usually be easily distinguished as follows: G. coerulescens 

 forms dense mats, has a dense, compact habit, with the upright branches short (8 to 15 mm. tall), flat- 

 tened, comparatively wide, much branched in a fairly regular, decompound manner; G. crinale usually 

 occurs in sparse clusters, has a slender, open habit, with the upright branches comparatively long (2 to 

 3 cm.), rounded or very slightly flattened, slender, usually sparsely and irregularly branched, some- 

 times simple, sometimes fairly regularly pinnate. 



Gel id him sp. indet. 



A single indeterminable fragment from Bogue Beach, Beaufort, N. C., September, 1905, is 4 cm. 

 long, about 0.5 mm. wide, and o.r mm. thick, narrow, flattened, sparsely pinnate, pink. This may 

 be a battered specimen of G. corneum or may be a portion of one of the larger, more tropical species. 



Order 2. Gigartinales Schmitz. 



Gigartininae, De Toni, 1897, p. 169. 



Carpogonial filaments and auxiliary cells usually occurring together in pairs, 

 forming definite procarps, sometimes occurring singly in the thallus. Cystocarps usually 

 immersed in the frond. Gonimoblast arising from an auxiliary cell after the fertilized 

 egg has fused with this by means of a usually short carpogonial process, not attached 



to a basal placenta. 



KEY TO FAMILIES. 



Gonimoblast consisting of a richly branched tuft whose branches are distributed without order 



within the inclosing structures; tetrasporangia usually cruciately divided . i . GIGARTINACE^ (p. 476). 



Gonimoblast divided into several lobes radiating inwardly in all directions; tetrasporangia 



zonately divided 2. RHODOPHYLUDACE^ (p. 478). 



Family 1. GIGARTINACE^E Schmitz. 



Frond terete, flattened, or foliaceous; dichotomously or pinnately branched, some- 

 times simple or irregularly lobate; structure cellular or filamentous, usually plainly fan- 

 like at apices; tetrasporangia scattered over the frond in the outer cortex, or grouped 

 in sori and immersed in the thallus, or borne in special protuberances (nemathecia), 

 usually cruciately, sometimes zonately, divided; antheridia usually in patches more or 

 less widely distributed over the surface of the thallus, sometimes in flasklike cavities 

 sunk in the outer cortex and opening to the exterior; carpogonia usually numerous on 

 the fertile portions of the thallus, usually produced singly on a three-celled carpogenic 

 branch associated with an auxiliary cell into a definite procarp; the fertilized egg fuses 

 with the auxiliary cell by a short process; the latter then gives rise to the gonimoblast, 

 consisting of a tuft of filaments richly branched in all directions; the branches of this tuft 

 are themselves richly branched and interwoven to form a structure of fertile and sterile 

 filaments almost without order; the apical cells of the fertile filaments (and sometimes 

 subapical ones also) form carpospores which lie in groups usually without order; fruits 

 often inclosed by a sterile jacket; these cystocarps usually occur scattered over the 

 thallus, immersed or more or less prominent on one or both sides, and communicate 

 with the exterior by one or more often inconspicuous pores. 



About 275 species, all marine, especially in cold and temperate seas. 



