184 SPHAERONECTES TRUNCATA. 



two are so closely allied that it is better to unite them under the older name, 

 irregularis Claus. 



The characters by which irregularis is separated from truncata are its pro- 

 portionately much larger nectosac, its thinner gelatinous substance, short 

 hydroecium, more upright somatocyst, and especially the bowed course of its 

 dorsal and lateral subumbral canals. I have not observed any specimen of 

 truncata, either large or small, which approaches irregularis in any of these 

 respects. Schneider ('98, p. 78), it is true, states that "von der irregularis 

 Form giebt es Ubergange zur gracilis Form," but he has not described these 

 supposed intermediates, nor has he analyzed the value of the diagnostic char- 

 acters. In view of the constancy of the course of the subumbral canals in other 

 Calycophorae, and the very marked difference in this respect between the two 

 species under consideration, this character alone would suffice to separate them, 

 and when we add to this the difference in form, irregularis certainly deserves 

 recognition as a good species. 



The form from the Indian Ocean recorded by Haeckel as Sphaeronectes 

 princeps ('88a, p. 34), and later described by him ('88b, p. 129), as Monophyes 

 princeps has not been discussed either by Chun or bj^ Schneider. Its subumbral 

 canals resemble those of irregularis, but the nectosac is proportionately even 

 higher, and the hydroecium is a mere groove, much as in certain Prayids. 

 Should it prove that these characters are constant, and that the specimen was 

 in fact a Monophyid, princeps would deserve recognition. But to determine 

 whether this is the case will require renewed examination of material agreeing 

 with Haeckel's account. A knowledge of its appendages would be particularly 

 valuable. 



The other species of Monophyes mentioned by Haeckel ('88b, p. 128) 

 are M. diptera and M. hydrorrhoa. The first of these is applied to the posterior 

 nectophore of Diphyes subtilis (p. 347), first described by Chun ('85) as the 

 "primary bell" of S. truncata {"gracilis"); the second, described merely as 

 being similar to the former, is no doubt the same. M. primordialis Chun ('82) 

 is a synonym of Muggiaea kochii Will, to the "primary" nectophore of which 

 it was applied. 



Sphaeronectes truncata (Will) Schneider. 



Ersaea truncata Will, '44, p. 82, taf. 2, fig. 2S. Eudoxid. 



Diphiphijm incrmU Gegenbaur, '53, p. 9, taf. 16, fig. 3; Clacs, '74, p. 27, taf. 4, figs. 1-4; Fewkes, 



'81, p. lG(i, pi. 6, fig. 12; Haeckel, '88b, p. 107; Chun, '92, p. 8.5. Eudoxid. 

 Sphaeroiwdes l^oUikeri Huxley, '59, p. 50, pi. 3, fig. 4; Haeckel, '88b, p. 130; Chun, '92, p. 84; 



Agassiz anil Mayer, '99, p. 177, pi. 17, fig. .53. 



