PAPENFUSS: CLASSIFICATION OF THE ALGAE 185 



classification of the red algae and other groups. In the course of time, especially 

 through the efforts of Greville (1830), Harvey (1841, 1849) and J. Agardh 

 (1842, 1851, 1852a, 1852b, 1852e, 1863, 1872, 1876, 1879), increasing emphasis 

 was placed on the finer details of the structure of the thallus and the reproduc- 

 tive organs. With the appearance of J. Agardh's work of 1842, the manner of 

 division of the tetrasporangia, whether tetrahedral, cruciate, or zonate, was 

 also introduced into the classification of these algae. These are characters that 

 in general are still considered important in the delimitation of taxa. 



As regards the characters offered by the structure of the cystocarp, J. 

 Agardh's system, which was the standard one for some fifty years, took into 

 account only the mature cystocarp. The multitude of significant characters 

 presented by the ontogeny of this organ thus remained concealed, with the 

 result that the system of J. Agardli, like those of his predecessors, contained a 

 great deal that was artificial. 



The present period in the classification of these algae, which Sjostedt (1926, 

 p. 85) has termed the embryological period, was ushered in by Schmitz's epoch- 

 making paper of 1883. Although Nageli (1861), Bornet and Thuret (1866a, 

 1866b, 1867, 1876, 1878, 1880), Solms-Laubach (1867), Janczewski (1876), and 

 Schmitz (1879b) had worked out in some detail the development of the cysto- 

 carp, the significance of the differences in the development of this structure in 

 different forms did not become apparent until 1883. On the basis of the funda- 

 mental differences in the ontogeny of this organ, especially as regards the place 

 of formation and the function of the auxiliary cell, Schmitz later (1889, 1892, 

 and in Schmitz and Hauptfleisch, 1896-1897) proposed a regrouping of these 

 algae along lines that portrayed a much more natural arrangement than had 

 yet been possible. Schmitz (1892) divided the Florideophycidae into the four 

 orders Nemalionales, Gigartinales, Rhodymeniales, and Cryptonemiales. 



Since comparatively few forms had been thoroughly investigated when 

 Schmitz proposed his system, it was to be expected that further knowledge Avould 

 necessitate revision of this system. Although Schmitz's four orders are still ac- 

 cepted, additional developmental studies have shown that they should be re- 

 constituted and it has been necessary to create two additional orders. The first 

 major emendation of Schmitz's system was by Oltmanns (1904), who, among 

 other changes, erected the order Ceramiales for those Rhod\m"ieniales of the sys- 

 tem of Schmitz in which the auxiliary cell is formed after fertilization of the 

 carpogonium, namely, the families Ceramiaceae, Delesseriaceae, and Rhodomela- 

 ceae (including the Dasyaceae as currently recognized). In 1923 Kylin estab- 

 lished the order Gelidiales for the family Gelidiaceae, which Schmitz, and fol- 

 lowing him Oltmanns, had placed in the Nemalionales. Still later Kylin (1925) 

 founded the order Nemastomales for the families Nemastomaceae and Rhodo- 

 phyllidaceac (previously placed in the Cryptonemiales and Gigartinales, respec- 

 tively) and Sjostedt (1926) erected the order Sphaerococcales for the family 

 Sphaerococcaceae (previously placed in the Gigartinales). but these two orders 

 were subsequently reduced by Kylin (1928, p. 113; 1932, pp. 71, 72, 76-79) 

 under the Gigartinales. Recently Feldmann (1952) established an order Bonne- 

 maisoniales. Although the genera comprising this order do not appear to be 

 closely related to the other members of the Nemalionales (in which order the 

 Bonnemaisoniaceae have been placed in recent times), the points of departure 



