270 SIR C. ELIOT ON NUDIBRANCHS [NoV. 29, 



lamina. The foot is strongly grooved in front, but not notched. 

 On each side of the mouth is a large but not very distinctly 

 shaped lump, which seems to represent a retractile and furrowed 

 tentacle. 



The labial armature consists of a dense mass of light yellow 

 bent rods, not bifid, exactly like those in Bergh's plates of 

 0. miamirana. The radula is large, broad and tough, yellow 

 behind, dark brown in front; it consists of 120 rows, the widest 

 of which have at least 1 30 teeth on each side of the rhachis. ISTo 

 rhachidian thickenings are visible, but otherwise the radula closely 

 resembles that of 0. miamirana. The first teeth bear two strong- 

 denticles on each side of the central cusp ; the next 10-15 are 

 denticulate on the outer side only, bearing as many as 10 denticles. 

 The remainder are simply hamate. The outermost are smaller 

 and rather irregular, but not denticulate. 



The specimen is clearly an Orodoris and closely allied to 

 0. miaoniraoia, particularly the specimen described by Bergh 

 (1. c. p. 71) as coming from Zamboanga. It is, however, super- 

 ficially extremely unlike the preserved specimen of 0. miamirana 

 given me by Dr. Willey, and I hesitate to regard it as a mere 

 variety. The main difference is that whereas in 0. miaonirana 

 there are ridges on the back foi'med by compound tubercles, there 

 are in this form a large number of narrow longitudinal as well as 

 transverse ridges which pass over the tubercles as well as the 

 general surface of the back. 



Hexabranchus Ehr. 



[See (1) Bergh, S. R. Hefte xiii., xvi., and Supplem.-Heft i. 

 (2) Eliot in Gardiner's Fauna and Geog. of Maldive and Laccadive 

 Archipelagoes, vol. ii. part 1 (1903). (3) Bergh in Schauinsland's 

 ' Reise nach dem Pacific : Die Opistobranchier.'] 



The Hexabranchidaj, which are very common in the Indo- 

 Pacific, but not recorded from other seas, are large doridiform 

 animals of brilliant coloration and active movements. They difier 

 from the ciyptobranchiate Dorids chiefly in having no branchial 

 pocket but a circle of separate branchial tufts, each of which con- 

 tracts when touched into a temporary hollow which forms at its 

 base. The texture is soft and smooth, the shape flattish, the 

 mantle-margin ample, and the tentacles foliaceous. There is a 

 strong labial armature, and the radula is similar to that of many 

 Dorids, consisting of simply hamate teeth with the formula oo.O.oo . 

 The verge is extremely long and the nervous system much 

 concentrated. 



Bergh observes {I. c. (3) p. 225): "Eine Reihe von etwa 20 Arten 

 ist angegeben welche zum allergrossten Theil doch wohl nur 

 Varietaten oder Localformen einer selir verbreiteten langst 

 erwahnten Art sind, des Hex. lacer Cuv." * My own observa- 

 tions support this, as far as the three forms here mentioned are 



* It seems to me quite clear that Cuvier's Doris lacera is a Se.vahrancJiiin, not a 

 Doridopsis. 



