114 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



ments or immersed in the frond ; antherozoids formed from the cells of 

 the protuberances or the superficial cells of the frond ; cystocarps com- 

 posed of few spores arranged end to end in a few rows, or in filaments 

 which branch slightly; tetraspores zonate or cruciate, stalked or 

 attached laterally to the filaments of the frond or protuberances. 



A small order, more abundant in tropical seas than on our coast, comprising species 

 which in habit resemble lichens rather than algse. A few species, as Peyssonnelia 

 squamaria and P. australis, attain a considerable size, and 'are distinctly foliaceous. 

 The greater part of the species, however, form closely adherent crusts, which are 

 sometimes more or less gelatinous and sometimes slightly calcareous. The structure 

 flf the fronds is simple. From a horizontal base, composed of a single layer or a few 

 layers of cells, arise vertical filaments, which in some genera are densely united so as 

 to form a parenchymatous frond, or in others are only slightly held together by a 

 gelatinous intercellular substance. The fructification is found either in external 

 raised spots or sunk in the frond. The antheridia are either formed directly from 

 the cells of the filaments which constitute the protuberances or from the external 

 cells of the fronds themselves. The tetraspores are either cruciate or zonate, and 

 their position constitutes an important generic mark. The development of the sys- 

 tocarps is known in only a few species. In Peyssonnelia, according to Dr. Bornet, 

 the procarp is formed from the cells of the filaments, which form the protuberances. 

 The upper cell elongates and forms the trichogyne, and the fertilization consists 

 merely in the change of the cells of the procarp into spores, thus constituting a very 

 simple form of cystocarp, to which Zanardini has given the name of cystidie. Ac- 

 cording to Prof. Fr. Schmitz, in Cruoriopsis cruciata, Dufour, there are winding fila- 

 ments like those described by Thuret and Bornet in Dudresnaya. We have but few 

 Squamariece on our coast, and the study of the suborder cannot easily be pursued 

 with us. 



PETSSONKELIA, Decaisne. 



(Named in honor of J. A. Peyssonnel.) 



Fronds horizontally expanded, attached by the under surface ; sub- 

 stance parenchymatous throughout; fructification in external convex 

 protuberances (nemathecia) composed of slender parallel filaments, on 

 which are borne the antheridia, cystocarps, and tetraspores; anthero- 

 zoids produced in all the cells of the nemathecial filaments ; tetraspores 

 cruciate, oblong, sessile or shortly stalked ; cystocarps composed of few 

 spores, placed one over another in one or two rows or in short, branch- 

 ing filaments. 



A small genus, comprising probably not more than twelve or fifteen good species. 

 P. squamaria, common in Southern Europe, is not known with us. It may be that 

 several of the species described by Crouan in the Annales des Sciences and the Florule 

 du Finistere occur with us ; but it must be confessed that from the description given 

 by Crouan it would be by no means an easy matter to recognize them. Those who 

 have an opportunity for dredging on shelly bottoms at localities like Gay Head, Block 

 Island, Montauk, or Eastport should make a careful search for species of the present 

 genus. 



