22 AMERICAN HVDKOIDS. 



"Gonosome. — Gonophores planoblasts or hcdrioblasts." Ho uses the adtlitional genera 

 Hypanihea, Calam-plwra, Hebella, and Ilalisiphonia. 



Marktanner-Tnrnerotscher (1890)^ gives the folloMdng defimtion of the family "Canipanu- 

 laiiidi^." 



Hydrolheken meist auf deut.licheu, weUn aiich kurzen Stielchen aufsitzend, von glocken- oder rohrenformiger 

 Gestalt. Hydroeaiilus mono- oder polysiphon, im letzteren Falle aber keine axials Rohre vorhanden, von welcher 

 die Stielchen sammllichcr vorhandenen Hydrolheken entspringen, sondern mehrere Rohren gleichmassig an der Bil- 

 dung von hydrothekentragenden Stielclien betheiligt. 



This definition is practically the one adopted for the present work. He recognizes the 

 genera Campanularia, Ohelia, Tliyrocyphus, Eucopella, Hypanthia, ,Halisvplionia, Lafoeina, 

 CalyceUa, Hebella, Opercularella, and Clytia. 



Levinsen, 1893,- removes the genera CalyceUa, Campanulina, Lafoeina and C'uspedella 

 from the Camiiamdaridse and places them in the Campanuluiidse, and combines the genera 

 Ohelia and Gonothyrxa in the old genus Laomedea. 



Schneider, 1897,^ uses the spelling "Campanularidse" and combines Hincks's four families 

 Campanulariidx, Campanulinidse, LeptocypMdse, and Lafoeidse in one, and includes practi- 

 cally all of the CampanularidfB as usually understood in the one genus Campanularia; a scheme 

 which would lead to fconfusion worse confounded and render the work of the systematists in 

 this group hopeless, except when he deals wdth a very limited number of forms. Even here 

 his success would be due to ignorance rather than to scientific acumen. 



No systematic treatise of serious import for our discussion appeared between 1897 and 

 1909, when two works of monographic form appeared from Scandinavian writers. 



One of these, Jaderholm's,^ is notable for its exceptionally fine plates, which, in the opinion 

 of the writer, have never been surpassed in clearness and fidelity to the original, in works on 

 the Hydroida. This author (p. 13) defines the family at some length and makes the pos- 

 session of a well-defiiied diaphragm a family character. He recognizes and defines the follow- 

 ing genera (pp. 16-20) : Clytia, Hebella, Tliaunnantias, Ohelia, Gonothyrsea, Campanularia, 

 Galanthula and gives well defined keys to the genera and to the si:)ecies under each genus. 



In the same year (1909) Broch'' published another valuable contribution to our knowl- 

 edge of this group. He defines the family Campanulariidse at considerable length under the 

 "Unterordnung Thecophora proboscoidea" and gives the historical rcAaew of the discussion 

 of the systematic position and Hmitation of the family. He recognizes and defines the genera 

 Campanularia and Laomedea (including the genera Laomedea, Gonothyrsea, and Ohelia of other 

 authors). He thus goes to an extreme not found in the works of other writers in throwing 

 together genera which are much more conveniently kept separate, in the opuiion of the present 

 writer. Wlule thei'e may be considerable argument on theoretical grounds for such a course 

 it undoubtedly leads to lumecessary and practically unsurmountable difficulties when large 

 numbers of species are to be handled and described. 



Mayer, in his Medusas of the World, vols. 1 and 2, the Hydruniedusse, 1910, has the last 

 word thus far appearmg on the systematic treatment of this group, considermg the subject 

 however from the medusse standpoint. It is impracticable to homologize his system with that 

 of writers on the Hydroida. The present writer after conference with Doctor Mayer ° was com- 

 pelled reluctantly to agi'ee with him that the difficulties in the way of arrivmg at a satisfactory 

 classification that would be available for systematists working both m the Hydroida and 

 Hydromedusse were such as to make the task impracticable in the present state of our 

 knowledge. 



' Hydroiden des k.k. natui'historischen Hofmuseums, p. 203. 

 2 Meduscr, Ctenophorer og Hydroider fra Gronlands Vestkyst, p. 35. 



' Hych'opolypen von Ro\'igno, nebst Uebersicht iiber das Sy.stem der Hydropolypen im Allgemeinen, Zoologische 

 Jalirbucher, vol. 10, 1897, p. 505. 



^ Northern and Arctic Invert., pt. 4, Hydroiden, 1909. 

 * Die Hydroiden der arktischen Meere, p. 183. 

 See Medusae of the World, vol. 1, p. 3. 



