54 AMERICAN HYDROIDS. 



PLUMULARIA Lamarck (in part). 

 Plumularia LAMARCK, Hist. Nat. des Anim. sans Vert., 1815. 1st ed., p. 123. 



Trophosome. Cifuosarc of stem not canaliculated, hydrocladia unbranched, pinnately dis- 

 posed, either alternate or opposite, without accessory branches of any kind, and each bearing 

 more than one hydrotheca. Hydrotheca^ with smooth margins; all of the neinatophores movable. 



Gonosome. Gonangia borne on the hydrocaulus or hydrocladia, simple sac-shaped or bottle- 

 shaped, and without phylactogonia or corbula-. 



Lamarck, in his first edition, includes all of the forms which would now be embraced in the 

 family Pluumlarida? in two genera: Antennularia, with the hydrocladia arranged in verticils, 

 and Plnmularia, containing all of the remaining forms. In 1S57 McCrady ' established the genus 

 Aglaoplienia to accommodate most of the Statoplea known at that time, in which he was followed 

 by Louis Agassiz- in 1862, and by Hincks ;i in 1808. The genus Plumularia was thus restricted to 

 very nearly its present signification, the other genera now included in the Eleutheroplea being 

 formed almost without exception to accommodate the great number of new and often highly 

 specialized forms which have been brought to light by the various deep-sea expeditions of the 

 last thirty years. 



The year 1816 witnessed the appearance of a work entitled Histoire des Polypiers Flexibles, 

 by Lamouroux, who divided the Plumularida- into two genera: Aglaoplienia, equal to Plumularia 

 of Lamarck, and Neinertesia, equal to Antennularia of Lamarck. This nearly simultaneous 

 appearance of two classic works with equivalent groups, but with distinct names, caused an 

 immense amount of confusion in the group and a needless addition to the synonymy, which 

 extended down to the appearance of Kirchenpauer's great work, the second part of which 

 appeared in 1876, in which the name Xemertexia is used. Subsequent works, however, have very 

 generally adopted Lamarck's nomenclature so far as these two genera I'lumularia and Antennularia 

 are concerned. 



Arrangement of (/enera adopted by various writers from 1815 to 1877. 



Lamarck Lamouroux lohnston McCrady Agassi?. Hincks Kirchenjiauer Allman 



(1815). (1810). (1847). (1857). (1865). (1868). (187G). (1877). 



Plumularia Aglaopheiria Plumulfii-ia I'lntniilaria^ Plumularia =-- Plumularia = Plumularia = Flutnularia + sev- 



+ Aylaujthenia= ci-al other geuera. 

 S(atoplea ol' later 

 writers. 



{Antennularia. 



Anteimutaria=l*emertena = Antennularia = Kemertesia --- Antennularia hemertesia . . 



It is interesting to note the regular alternation between Antennularia and Xemertesia, each 

 writer differing from his immediate predecessor. The name Nemertesia does not appear in 

 any prominent work on this group subsequent to 1876. and it is to be hoped that this per- 

 sistent ghost of Lamouroux will not reappear to disturb the much harassed synonymy of the 

 Eleutheroplea. 



As is usually the case with old genera which have been frequently subdivided, the genus 

 Plumularia can best be defined by a process of exclusion resulting in a preponderance of 

 purely negative characters. The group, as above defined, seems a natural division of the 

 Eleutheroplea, including about half of the American species of that division of the Plumularida?. 



The following key to the known American species of the genus Plumularia will, it is 

 hoped, enable the student to identify the forms mentioned in this work. It must be remem- 

 bered, however, that the arrangement is arbitrary at best, and it should also be borne in mind 

 that the arrangement of the interuodes is exceedingly inconstant in some species, that given in 

 the key being simply the predominant one in the species under consideration. 



1 Gymnophthalmata of Charleston Harbor, Proceedings of the Elliott Society, 1857, ji. 199. 



2 Contributions to the Natural History of the United States, IV, 1802, p. 358. 



3 History of British Hydroid Zoophytes, 18G8, p. 284. 



