THE APODOUS HOLOTHURIANS 



91 



his specimens from Funafviti to that form. Japanese specimens have 9-11 

 digits on each tentacle, while those from Zanzibar have from 9 to 13. 

 Tlie latter are interesting further as the host of tlie remarkable parasitic 

 bivalve, Entovalva mirabilis. Lamport's ('96) statement that the difference 

 in proportions between the anchors and plates posteriorly and anteriorly is 

 not due to a difference in the anchors, as v. Marenzeller ('81) says, but to a 

 remarkable difference in the plates, is borne out by my measurements. The 

 following table gives the figures involved, measurements in microns : 



Leptosynapta galliennii. 



Synapta galKennii Herapatli, 1865, p. 5. 



Synapta sarniensis Herapatli, 1865, p. 5. 



Synapta saruiensis Herapatli, 1865, pi. 1. 



Synapta sarniensis Lankester, 1868, p. 53. 



Synapta bergensis Ostergren, 1905a, p. cxxxii. Calcareous particles, fig. la. 



Length. — 100-300 mm., but usually about 150. 



Color. — Reddish, similar to that of inhcerens. 



Distribution. — Reported only from Guernsey (Herapath, Lankester), 

 Outer Hebrides (Mcintosh) and Norway, Sweden, and the Faroes (Ostergen). 

 Probably occurs along the entire coast of northern Europe with its outlying 

 islands. 



Remarks. — This Synapta is certainly closely related to inhcerens and is in- 

 termediate between that species and the following. Whether there is an un- 

 broken series between the true inhcerens and the Mediterranean macrankyra is 

 still uncertain, but for the present we may conveniently recognize the three 

 species. Ostergren ( :05a) considers the Norwegian form, which he calls ber- 

 gensis, as quite distinct from Herapath 's species, but the differences which he 

 mentions (15-17 digits instead of 13, terminal digits no longer than the others, 

 skin thicker and redder, slightly larger anchors, margin of plate not so con- 

 tinuously dentate, more holes in most of the plates) are so trivial, so very 

 variable, and so commonly correlated with the age of the individual, that, 

 when we consider he had only a single specimen of galliennii for comiDarison 

 and that a very large one (250 mm.), we are not justified in regarding the two 

 forms as specifically distinct; and this decision is confirmed by the fact that 



