i ultONAT.E AT()Hi:i.l.\. 569 



lappets. The stomach is Hat and shallow and the 4 lips are short and thickened. The 4 

 intcrradial septal mules are narrow and the pcnadial ostia wide. 'I he gasmc cirri are 

 arranged in 4 intenadial groups, each group arising trom a stout gelatinous stalk, and consist- 

 ing of So to 100 filaments. The canal-system of the bell resembles that of Periphylla. The 4 

 penadial ostia of the central stomach lead into a wide ring-sinus, which gives rise on its outer 

 side to 12 broad radial-canals in the radii of the tentacles and sense-organs. These radial- 

 canals branch at their ends and unite to form a marginal festoon canal. I he ring-muscle of 

 the subumbrella is very weak, but the subumbrella plates at the bases of the tentacles are 

 \erv prominent. 



There are 4 t;onads, each being a leaf-shaped hod\ folded so as to leave a deep groove 

 along iis middle line on the inner surface, and this groo\e causes the gonad to appear as if 

 double, although this is not truh the case tor each gonad is attached along a single line. The 

 gonads are orange-\ ellou , all other parts colorless. This is a surface species. Bigelow records 

 it from off the Pacific coast of Panama. 



Order SEMAEOSTOME^E L. Agassiz, 1862. 



Semaeostvmc.r, A'.A-M/, I-., iSh;, Conl. Nat. Hist. I'. S., \,,\. 4, pp. ij, i^. 



Semoslamj-, HAM kit. iSSo, S\ t. .ler Me, Insert, p. 4'i<|. 



Semttostomata, VAN tt. in- IN, iSSS. Jiibliothei :\ /.oologi, a. Heft. ',,pp.'>, 21; rood. Nordi chei Plankton, Nr. 1 1 , Acraspcda-, p. 45. 



Semaeoslomj-, M\AX, !) ' nd M'OIM hriiie .ler /o..l.. lid. i, p. 200; lyod, Fauna Arctica, Bd. 4, Lfg. 3, p. 504. 



Diseomtdune (in part), HAtcKtt., 1880, S\^t. der Medusen, p. 450. 



CHARACTERS OF THE SEMAEOSTOME^E. 



Scyphomedusae without a coronal furrow anil without pedaha. With a simple, central 

 mouth-opening, the 4 perradial angles of which are developed into large curtain-like or gelat- 

 inous lips. With hollow tentacles and marginal rhopalia. The gonads are in sac-like folds ot 

 the entodermal wall of the subumbrella. Without interradial septal nodes in the stomach. 



The families of the Semaeostomeae are as follows: 



(1) Pclagida- GE<;>:NBAI-R, 1856. The central stomach gives rise to completely separated, unbranched radiating pouches. 

 No ling-canal. Tentailes .irise from the bell-margin between the clefts of the lappi-ts. 



(2) Cy.ineid.e AcASIlZ, I... iS<i>. The central stomach gives rise to branched but completely separated radial-canals. 

 No ririL^-canal. Tentacles arise from the floor of the subumbrella. 



(3) Ulmarid.r HAM KM, 1880, sens ampl. The central stomach gives rise to simple or branched radial-canals which 

 are put into connection one uirli .mother hy a marginal ring-canal. 



A. Subfamily I'mbrosidii. The tentacles arise sine.lv from the clefts between the marginal lappets at the bell- 



margin. Protrusive, sac-like gonads, without subgenital pits. 



B. .Subfamilv Sthenonidii. The tentacles arise in linear clusters from the floor of the subumbrella. 



<7. Subfamily Aun-lidii. The tentatle- anj lappets arise from the sides of the ciumbrella above the margin. 

 Imayinated ^onajs with subgenital pits. 



Family PELAGID^E Gegenbaur, 1856. 



PtlagiJt, ilt'.i M!\I K, 1856, /fit. fiir wisM-n. /ool., H,l. S. pp. 210, 267. AOASSIZ, L., 1861, Cont. Nat. Hist. U. S., vol. 4, pp 

 121, 163. AGASSIZ, A., 1865, North AIIHT. Acal., p. 47. HASCKKL, 1880, Syst. dcr Medusen, p. 499. VON LKNDENFF.LD, 

 1884, Proc. Linnean Soc. Nn South Wales, vol. 9, p. 2(15. CIAVS, iXSi,, Arbeit. /ool. Inst. I'niv. \\'cin., B.I. 7, p. no. 

 AI.ASM/ AM> .\Kvi.i:, iSijS, Bull. Mus. Comp. /ool. at Harvard Collcgf, vol. -,:. p. r. -1'iAr s, 1883, Organisation und 

 Entwick. Medusen, p. 24. VAMIOH-I-N, njofi, Nordisclics Plankton, Nr. n, p. 45. 



1 AMU 1 CHARACTERS. 



Scyphomedusae with 8 or 16 marginal sense-organs, 4 perradial and 4 interradial, and, 

 when present, 8 adradial. 8 or more tentacles which arise singly from the clefts between the 

 marginal lappets. 16 to 64 maiginal lappets. The mouth is simple and cruciform, and is 

 situated at the extremity of an oesophagal tube, the 4 perradial corners of which are produced 

 to form 4 long mouth-arms, the tree edes ot which are complexly crenulated. The simple, 

 lenticular, central stomach gi\is rise to completely separated, radiating pouches the centrifugal 

 ends of which give rise to simple, unbranched lappet-pouches. There is no ring-canal. The 

 gonads occupy 4 interradial folds in the wall of the subumbrella. In some cases they project, 

 but they are usually sunken, forming 4 pits in the floor of the subumbrella. 



