LEPTUMEUL'S.E. 197 



and probably nearly related to the forms from which the Campanularian medusae have 

 developed (see A. Agassiz, 1865, pp. 124, 125; O. and R. Hertwig, 1897, Nervensyst. und 

 Sinnesorgane der Medusen, p. 155; Haeckel, 1879, pp. 121, 125; Brooks, 1895, pp. 301-303). 

 Haeckel goes so far as to state that the medusae of his genus Tetranema (fhaumantias) 

 are the primitive forms from which the Campanularian medusa? (Leptomedusae) have been 

 developed! 



Asexual budding of medusae upon the gonads is unknown in the Thaumantiadae. 



Brooks, 1895, shows that the marginal sense-clubs of Landicea contain no tract- of concre- 

 tions. Their cores are entodermal and they arise from the level of the exumbrclla nerve- 

 ring, above the velum, and are identical in all their anatomical relations with the sense-clubs 

 of the Narcomedusae and Trachymedusae. 



Haeckel, 1879, includes Gomonemus and the Williadi among the Thaumantiadae. 

 Gon ion emus is certainly not one of the Thaumantiadae, for it has marginal lithocysts; and 

 according to the researches of Hincks, 1872, and Browne, 1896, the Williadi are derived 

 from Tubularian hydroids and should be placed among the Anthomedusae. 



The Thaumantiadae may be conveniently, although somewhat artificially divided into 

 three subfamilies: 



1. Melicertinae, with simple, unb ranched radial-canals. 



2. Polyorchinae, in which the radial-canals give rise to blindly-ending side branches, 



and these side branches do not fuse with the circular vessel. 



3. Berenicinae, in which the radial-canals give rise to side branches, and these side 



branches connect with the circular vessel. 



A description ot the genera of the Thaumanriadie follows: 



SUBFAMILY MELICKRTINJE: With simple, unbranched radial-canals upon which the gonads arc developed. The lips are as 



numerous as the radial-canals. Ocelli, marginal sense-clubs, cordyli, and cirri are often present. There are no oral tentacles. 



Thaumantias ESCHSCHOLTZ, ifay^Tttranema+Thaumantias HAECKEL, 1879. 4 or more tentacles, 4 radial-canals, 

 and 4 simple lips. No marginal clubs or cirri. Hydroid: Thaumantias, 



Laodicea LESSON, 1845= Qctenema+ Laodice HAECKEL, 1879. 4 or more tentacles, with marginal clubs or cirri or both 

 between tentacles. 4 radial-canals, 4 simple lips. Hvdrmd: Cuspidelln. 



Mriirrrtum OK I;N, sfnsu AGASSIZ = Melicertella j r Mflirertum HAKCKKI, 1879. With 8 or more icnt.n lc-. S radial- 

 canals, 8 simple lips, ami without marginal sense-clubs and cirri. Hydroid: Mflicrrtum. 



t\ffliffrtissti HAI.CKJL, 1^70. \\'iili S nr more tentacles. 8 radial-canals and X lips. With mariMn.il i , , 



cirri. This is equivalent t<i Melicertis$a Mrlietrtidium HAECKEL, 1X70, p. 124. 



Orrhi'-tonui HAKCKEI., 1879. More than 8 radial-canals and the same number of lips. With or without marginal 

 sense-clubs and cirri. Development unknown. 



Timoides BlGELOW, 1904. 4 radial-canals. Ring-canal gives rise to blindly-ending, centripetal canals. Stomach upon 

 a peduncle. 4 gonads on the radial-canals. Numerous tentacles and cirri. Development unknown. 



SUBFAMILY POLVORCHIN.T-.: 4 or more radial-canals which give rise to blindly-ending side branches that do nut reach the circular 



vessel. Gonads upon radial-canals, or upon their side branches. Ocelli, marginal sense-clubs, and cirri are often pp-M-nt. 



Staurodiscu3 HAECKKI , 1879. 4 radial-canals, each of which gives rise to 2 blindly-ending side branches. Gon.ids upon 



4 mam radial-canals, also upon side branches. There arc marginal sense-clubs. Manubnum tubular, with 4 simple 



lips. Development unknown. 

 Ptychogena A. AGASSIZ, 1865. 4 radial-canals, which give rise to numerous blindly-ending side branches upon which 



gonads are developed. Manubnum wide and shallow. Mouth simple, large, cruciform opening. Development 



unknown. 

 Polyorckis A. AC.ASSIZ, 1862-65. 4 radial-canals, which give rise to many blindly-ending side branches. A number of 



free sack-shaped gonads arise from radial-canals. Bell-margin simple. Manuhnum long and tubular, and tin-p- 

 are 4 simple lips. The ring-canal is simple without centripetal branches. 

 S(ri/>f>sia, TORRKY, 1909. Similar to Pol \orch is, but with a gastric peduncle and without pinnate branches on the 



radial-canals distal to the gonads. (See Appendix.) 

 Xpirorodon HAKCKEL, i^jy^Goneomeantlrus, KIRKPATRKK, 190}. Similar to /'O/VOT/IIJ, but ring-canal gives, rise to 



blindly-ending centripetal branches and bell-margin divided into lappets. Development unknown. 



SUBKAMILY BIRHWICIN.'}-;: Radial-canals branch and all branches connect with circular vessel. Lips as numerous as main 

 radial-canals. Ocelli, marginal clubs, and cirri often present. 



Cannota HAFCKEL, 1879. 4 main radial-canals each of which gives rise in 2 simple side branches, and thus 12 canals 

 connect with the circular vessel. There are 12 gonads, I upon each terminal branch of the radial-canals. 



Curifria PERON, 1807 = Btrcn ice HAECKKI,, 1879. The 4 mam radial-canals give rise to non-dichotomoua side 

 branches, and the side branches also branch. Gonads on the terminal branches of the radial-canals. 



Dichotomia BROOKS, 1903. 4 mam radial-canals all of which divide dichntonmuslv twu nr more times. Tin- 

 extend outward from the sides of the stomach over the radial-canals and their branches. 



DipUurosoma AXEL BOF.CK, 1866 = Tttracannota MAVKR, 1900. "\ or more main radial-canals, some or all of uhuh 

 give rise to non-dichotomous branches. Gonads on the canals adjacent to the manubnum. According to Browne, 

 the hydroid appears to be Cuspidella? 



Toxorchis sens, emend., HAECKKL= Toxorcki$+ Cladotanna HAECKEL, 1X79. 4 or more main r.ult,il-t anal', u Inch 

 branch dichotomously one or more times. Tin- gonads are upon the outer branches -.f the radial-canals near tin- 

 circular canal. 



Netocertoitki M\YKR, 1900. 8 main radial-canals, which branch dichotomously. The gonads extend outward from tin- 

 sides of the stomach along the radial-canals. 



