13G AMERICAN HYDROIDS. 



I have nut seen this species and him- ropied the description of Allnian entire. The species 

 evidently belong to the Xi/iitlm-im/i group. and appears to be an exceptionally well-marked form. 

 TIJI. In the Museum of Comparative Zoology, Cambridge, Massachusetts. 



SYNTHECIUM ROBUSTUM, new species. 

 (Plate XLI, figs. 4-6.) 



Tropkosome. Colony attaining a height of '2$ inches. Stem not fascicled, straight, without 

 hydrothecse In-low the proximal branches, hydrothecate above, divided into irregular internodes. 

 Branches strictly opposite and divided into branchlets; main branch straight, giving off pairs of 

 strictly opposite branchlets and bearing as a rule three pairs of hydrothecse between adjacent 

 branchlets: internodes variable, the must common arrangement being one for each pair of branch- 

 lets. there being two pairs of hydrothecse above and one below the branchlets: branchlets straight. 

 with a tendency toward an internode to each pair of hydrothecse. Hydrotheca- tubular, short, 

 stout, extensively immersed, only a small part of the distal adcauline side being free; margin 

 neither constricted nor flaring, and without ornamentation, but sometimes broadly sinuated; 

 aperture round, sometimes subtriangular. No operculum. 



Gonosome.- (Jonangia springing from the interior of hydrothecie. terete, heavily annulateil. 

 witli a very small tubular neck and round aperture. The specimens were dried, and the gonangia 

 greatly distorted, making it necessary to attempt a somewhat uncertain reconstruction in the 

 drawings. 



D!x1ril>i(l!<ui.All><itr><x Station U7T(i. hit. S. :,-2 41'. long. W. U'.P 55' 30", 21 fathoms. 



This species has shorter and more extensively immersed hydrotheeie than any of the others 

 of the genus thus far described. 



TI/JI, xl!<l,x. Cat. No. 1071-i, U.S.N.M.; Cat. No. iscTo. Museum of the State University 

 of Iowa: also in the collection of the author. 



SYNTHECIUM CYLINDRICUM (Bale). 



(Plate XLI, \\j>. 7.) 



Serliiliinllii i-i/liiiilfii-ii 1! M.I:. 1'roc. Linn. Sue. New Si;}iitli Wales, :M. ser., Ill, isss, p. 765. 

 ,v, i-iiiliin llu rii/lmiririi HARTI.AI-B, Revision der Sertularella-Arten, 1HOO, p. r>r>. 

 SertuHaretta luilf-inu TORREY, Hyilrniila of the Pacific Coast, 1902, ]>. 61. 



'' Hydrocaulus about half an inch in height, simple or slightly branched, divided b\- oblique 

 joints into internodes of moderate length, each bearing a hydrotheca on its upper part. Ilvdro- 

 theca- adnate nearly half their height, large, stout, cylindrical, smooth, usually somewhat rounded 

 at the base, curved outward: aperture looking outwards and upwards, not contracted, margin 

 entire, very slightly everted, peristome often double or triple. 



" Gonosome. Gonothecse (male) arise from within hydrothecae; long, tubular, somewhat 

 broader than hydrothecae, and five or six times as long as broad. A single tubular gonophore." 



'I)!xtril>iit!i>i,. Port Jackson, Australia (Bale): San Diego Bay, California, 5 to l~2 fathoms 

 (Tor rev). 



The description and figures of X r1ul<ir< U Jmli <-in/i Torrey almost exactly agree with those 

 of *S'. <-i/l unli'ii-,1 Bale, leaving no room for doubt of the identity of the two species. Hartlaub 1 

 suggests the probable identity of X. i-yliiiilrim and X, I'fiilnrtii int< i/i'ii Allnian.'' The original 

 figures of these two species are so different that one is at a loss to imagine why this suggestion 

 was niade.- 



1 have not seen this species, and have copied the above description of the trophosome from 

 Bale, and that of the gonosome from Torrey. 

 . 111 the Australian Museum '.. 



'Revision ilt-r Si-rtularclla-Artt-n, I'.ion. p. ti.'i. Mniii-iiul "I tin- Linnn-an S..cii-ty, XII, 1*7-4, pi. Mil, fig. 4. 



