692 Reports on the Zoological Collections made in Torres Straits, 1888-1889. 



In 1885 Erdmann, investigating the anatomy of a number of forms which, to 

 judge from their outward characters, should all be relegated to the genus Epizoan- 

 thus, discovered that, in reality, they belonged to two distinct natural genera, 

 distinguished by the circumstance that some of them possessed a single mesogloeal 

 sphincter muscle, whilst in others the sphincter was endodermal. Amongst 

 the latter was Schmidt's species P. axinellce. Those species which possessed a 

 mesogloeal sphincter muscle Erdmann retained in the genus Epizoanthus. Those 

 which had an endodermal sphincter, he placed in the genus Palythoa, ignoring 

 P. mammillosa, and adopting P. axinellw as typical of the genus, thereby excluding 

 the type species, as well as numerous closely allied forms which had hitherto borne 

 the name Palythoa. 



It was now necessary to find another name for these forms, and Erdmann 

 consequently revived Lesueur's genus Corticifera, a genus which, as we have 

 pointed out above, was synonymous with Palythoa, but had to give place to that 

 genus on the gromids of priority. To the former definition of the genus 

 Corticifera Erdmann added certain anatomical characters — namely, the " micro- 

 typal " (brachycnemic) arrangement of the mesenteries and the presence of a single 

 mesogloea sphincter muscle. These anatomical characters have been shown to be 

 present in all the species recently investigated which are included in Lamouroux's 

 Palythoa and in Lesueur's Corticifera, including the type species C. glareola 

 (re-examined by M°Murrich, 1889, p. 122). It therefore appears that they all 

 belong to one and the same morphological genus, which, as we have shown, must, 

 according to the laws of priority, be known as Palythoa. To sum up, the 

 argument may be briefly stated as follows : — ^Palythoa, Lamx. = Corticifera, Les. = 

 Palythoa, Verrill, &c. Schmidt and others extended Palythoa to include P. 

 axinellce and similar species, thus, unconsciously, making the genus Palythoa both 

 macro- and brachycnemic. 



Erdmann restricted the genus Palythoa to the non-typical macrocnemic exten- 

 sion, and revived Corticifera for the typical brachycnemic species. We restore 

 Lamouroux's genus, discard Corticifera, and erect a new genus, Parazoanthus, for 

 P, axinellce and allied species. 



As regards P. mammillosa, the type species of Palythoa, we may say 

 that we are strongly inclined to regard C. lutea of Hertwig (1888, p. 44, 

 PI. I., fig. 6) as being synonymous with P. mammillosa. M'Murrich agrees with 

 us in regarding Hertwig's identification of his West Indian form with Quoy and 

 Gaimard's Mammillifera lutea, from the Fiji Islands, as doubtful in the extreme ; 

 but he is inclined to believe Hertwig's species to be identical with C. glareola, which 

 he describes (1889, p. 122). However this 'may be, we feel quite justified in 

 assuming that the anatomical characters of P. mammillosa are similar to those of 

 all the other species possessed of similar outward characters, which have been 

 anatomically examined. 



