120 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



A large order of filamentous algae, many of whieh are monosiphonous throughout, 

 while others are corticated either throughout or partially. The position of the anthe- 

 ridia and tetraspores varies in the different species. The cystocarp is a favella, which 

 is either naked or surrounded by an involucre arising from the cells below the carpo- 

 genic cells. In cases where the frond consists of an axis with dense whorls of branches 

 the favellae may be partly concealed but not really immersed in the frond. The order 

 is tolerably distinct. The fronds resemble closely those of the Wrangeliece, and on 

 the other hand the order passes gradually into the Cryptonemiece by the genera Gloiosi- 

 phonia, Calosiphonia, and Nemastoma, in which the fruit is properly a favella, but is im- 

 mersed in the comparatively dense outer portion. of the frond instead of being free as 

 in the Ceramiece. In fact, it is difficult to say in which suborder Gloiosiphonia should 

 be placed. 



1. Tetraspores external, occupying the place of a branchlet or ultimate 



cell . 3 



2. Tetraspores wholly or partly immersed, formed from the corticating 



cells , . .'«.;. 4 



3. Fronds filamentous, monosiphonous, or with a false cortex composed 



of descending filaments, favellse naked or with only a rudiment- 

 ary involucre Gallithaminon. 



Fronds filamentous, monosiphonous, dichotomous, favellse involu- 

 crate Griffithsia. 



Fronds filamentous, branches densely whorled on the axis, favellse 

 involucrate Halurtis. 



Fronds compressed, corticated, decompound-pinnate, favellse involu- 

 crate Ptilota. 



4. Fronds filamentous, monosiphonous, cortications at the nodes and 



extending over the internodes Geramium. 



CALLITHAMNION, Lyngb. 



(From Kal?iog, beauty, and tiauviov, a small shrub.) 



Fronds filamentous, branching, filaments either monosiphonous 

 throughout or becoming corticated by the growth of descending, rhizoi- 

 dal filaments ; antheridia forming hemispherical or ellipsoidal tufts on 

 the branches ; cystocarps composed of irregular masses of roundish 

 spores covered by a gelatinous envelope (favellse) ; tetraspores tripartite, 

 cruciate, or pofysporic ; seirospores present in some species. 



A large aud beautiful genus, of which nearly 150 species have been described. Al- 

 though the genus has been divided into a number of smaller genera, the number of 

 species still retained in Callithamnion proper is large. Nsegeli, in his paper on the Mor- 

 phology of the Ceramiacese, divides Callithamnion into a number of genera and sub- 

 geuera, but we have thought best to retain the genus in an extended sense, regardiug 

 Nsegeli's division as subgenera. Spermothamnion, included by Nsegeli in Herpotliamnium, 

 has been separated because the cystocarpic fruit is not strictly a favella as in Callitham- 

 nion proper. Sevrospora is still retained, although it is possible that it could safely bo 

 separated as a distinct genus. The frond in Callithamnion is composed, in the beginning, 

 of rows of cells arranged in branching filaments. In the subgenus Ehodochorton, whose 

 relative position is doubtful because the cystocarps have not yet been observed, there 

 are procumbent filaments, from which arise vertical branching filaments. In the other 



