Br. J. Allan 'Thomson — Brachiopod Nomenclature. 373 



parts appearing April-July, 1827, and August-November, 1827. In 

 the meantime he described some new species of Mexican birds in a 

 paper -which appeared in tbe Philosophical Magazine in May and 

 June, 1827, referring some of them to the new genera proposed in 

 the earlier written but later published paper. The International 

 Commission held that Swainson's bird genera in the Philosophical 

 Magazine of 1827 are monotypic, and according to Article 30 (c) the 

 species mentioned are types of their respective genera. Therefore, 

 these types must take precedence over the designated types of 

 Swainson which occurred later in the Zoological Journal of 1827. 

 The argument on which this opinion was based was stated as 

 follows : — 



" In order to fully realize the bearing of the principle involved in 

 the present case, let us ask ourselves the question : What was the 

 type of these genera in the interim between the prior publication in 

 the Philosophical Magazine and the type designation in the Zoological 

 Journal? During these 'two or five months (as the case may be) ' 

 the genera rested solely on the generic name and the single species 

 described in the Philosophical Magazine. No other species was 

 known to belong to these genera during the two or five months. 

 Surely during that period these generic names were monotypic, and 

 could rightfully have no other type than the only species then 

 described. But if a genus once has a rightful type there is no way 

 under the international rules to substitute another later. If a 

 genus has been monotypic for two or five months, or any other 

 length of time, subsequent publication cannot alter its status however 

 plausible may be the argument otherwise, and this status can be no 

 more ' subject to change' than ' designation of the type ' itself. 



"Any interpretation other than the one here followed might give 

 rise to serious complications. For instance, to admit that a later 

 article can undo the types actually (though possibly unintentionally) 

 published in an earlier article, as in this case, would make it 

 possible for an author to publish a genus as monotypic and then, 

 years later, to alter his type in some manuscript the publication of 

 which had been purposely or unintentionally delayed for decades. 

 Thus, unless an author definitely stated that a genus was monotypic, 

 no genus originally published with mention of only one species could 

 be looked upon as having the genotype definitely established until 

 after the author's death, and afterit was proved that he left no 

 unpublished manuscript behind him." 



The case of Spirifer is extremely similar but simpler. From 1818 

 to 1821 the genus was monotypic so far as Sowerby was concerned, 

 and included only Spirifer cuspidatus, and this, therefore, cannot be 

 displaced as the type of the genus if the international rules are to 

 be adhered to. 



Thanks to Punch, the name Ichthyosaurus has become a household 

 word in a more complete sense than Spirifer, but it also can be used 

 only in contravention of the international rules. It was proposed 

 by Conybeare in 1821, but it is preoccupied by Proteosaurus, Home, 

 1819. Lydekker ' stated the case thus: "There is no real 

 1 E. Lydekker, Cat. Foss. Bejpt. Brit. Mus., pt. ii, 1881, p. vii. 



