284 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Hartlaub (1892, 1913) that the gonads are sufficiently different to 

 separate it. In Leuckartiara these are fundamentally horseshoe 

 shaped ; the arms, it is true, are transversely folded, but the folds are 

 permanently connected next the interradius. In Neoturris, on the 

 contrary, the vertical series of transverse gonad folds are not con- 

 nected with one another at the inner (interradial) ends, while the 

 interradial surface of the manubrium is occupied by an irregular net- 

 work of sexual thickenings. The figures by Maas (19045) and Hart- 

 laub (1913) show the two gonad types very clearly. (For further dis- 

 cussion see Hartlaub, 1913, p. 325.) 



So far three species of Neoturris have been recorded from the Indo 

 Pacific — the Turris papua of Lesson (if it be actually a Neoturris) , 

 T. pelagica Agassiz and Mayer, and T. fontata Bigelow [Turris hrevi- 

 cornls Murbach and Shearer (1903) is probably a Leuckartiara, as 

 Hartlaub, 1913, p. 335, points out]. 



There is nothing in the original account and rather diagrammatic 

 figure of pelagica (Agassiz and Mayer, 1902) to separate it from the 

 Atlantic N. pileata. And two specimens in the present collection 

 also agree with N. pileata in general form, structure of the gonads 

 and tentacles, degree of lobation of radial canals, and absence of 

 ocelli, though they have more tentacles than have ever been recorded 

 for the Atlantic form. But the number of tentacles is so variable 

 (Hartlaub, 1913) and the discontinuity between the two forms so 

 small (up to 90 for Atlantic, 100-120 for Phillipine specimens) that 

 it does not justify separating the Pacific form specifically. And the 

 Philippine specimens are apparently only an older stage of pelagica 

 Agassiz and Mayer; at least, the only important difference — larger 

 size and greater number of tentacles — can be readily explained as 

 concomitants of growth. In short, it appears that in Neoturris, as in 

 Leuckartiara, one species ranges over both the Atlantic and the 

 Pacific. And comparison of the accompanying photographs (pi. 39, 

 figs. 7-8) with Hartlaub 's (1913) figures will show how closely speci- 

 mens from the two oceans agree in all essential features. 



It is possible that the Turris papua of Eydoux and Souleyet (1841) 

 also belongs to this compound form, for its gonads are clearly of the 

 Neoturris type. But it differs from pileata in having very few ten- 

 tacles (10-11), and this is also true of Lesson's (1830) Aequorea 

 mitra, later called by him Turris papua. 



N. fontata is distinguished from all other members of the genus by 

 the presence of ocelli, of exumbral sense pits, and of tentacular ostia, 

 together with a small number (20±) of tentacles, and of many per- 

 manently rudimentary tentacular knobs. 



