1909] Torrey-Kleeberger: Threi Species of Cerianthus. 119 



oesophageal lining, in the position of, but not to be regarded as, 

 a second siphonoglyph. 



The mesenteries correspond in number to each set of tenta- 

 cles. Their arrangement is shown semi-diagrammatieally in fig. 

 I. The longest six are in reality Longer in proportion to the 

 others than they appear to be in the figure. Four commonly 

 reach the neighborhood of the terminal pure. The longest ten 

 alone bear gonads, as indicated by the heavier lines. Alternat- 

 ing for the most part with them are much shorter mesenteries 

 which bear much-coiled mesenterial filaments along their free 

 edges. The directives extend little or not at all beyond the lower 

 edge of the siphonoglyph. In the growing zone, opposite the 

 siphonoglyph, are several short mesenteries that do not reach 

 below the lower edge of the oesophagus, but are readily seen in 

 serial sections and show by their length the order of their devel- 

 opment. There is no sign of the arrangement of the mesenteries 

 into the groups of four characteristic of C. membranaceus, 13 ('. 

 borealis Yen-ill 14 and ('. jjohnsoni. In this respect, ('. aestuari is 

 especially simple. 



True acontia are wanting, as well as the filamentous pro- 

 cesses of the mesenterial filaments found in C. benedeni and C. 

 johnsoni. 



The species is hermaphroditic. Each gonad contains, side by 

 side, in separate follicles, developing ova and sperm. 



The essential characters of ('. aestuari are: 



1. Coloration: column streaked and mottled with brown: 

 tentacles delicately banded, with frequently a single pair more 

 deeply and conspicuously colored. 



2. Small number — not more than 34 each — of marginal and 

 labial tentacles. 



3. Thin column wall. 



4. Long oesophagus with broad siphonoglyph that does not 

 reach lips. 



5. Essentially but two orders of mesenteries, corresponding in 

 number to each set of tentacles. 



6. Absence of acontia, true or false. 



isFaurot: Arch. Zool. Exp. et Gen. (3), III, p. 43. 1895. 

 nKingsley: Tufts' College Studies, No. 8, June, 1904. 



