354 bulletin: museum of compakative zoology. 



perforated plates ; while most of them are flat, many are curved aud the resem- 

 blance to those iu the pedicels is occasionally marked. The calcareous particles 

 impart a very considerable rigidity to both body wall aud tentacles. The largest 

 specimen before me is 60 mm. long and 20 mm. in diameter, the smallest is 

 only about one-fifth as long. All the specimens agree iu color, though the 

 depth of the shades shows considerable diversity. The darkest specimens are 

 nearly or quite black, except for the ventral surface which is more or less whitish, 

 sometimes in very marked contrast. In lighter specimens the dark shade is brown 

 or gray and the ventral surface is yellowisli or grayish. In only a few specimens 

 is there a lack of sharp contrast between the upper and under surfaces. As a 

 rule, the anterior part of the lower surface is colored like the back and the tenta- 

 cles are always very dark. 



It is a matter of some interest that Dr. Coker should have met with this Pa- 

 namic species in Peruvian waters -^ there seems to be no good reason for doubting 

 that his specimens are identical with Selenka's species. He took two specimens 

 in the Bay of Sechura, in five fathoms, but at the Lobos de Afuera Islands he 

 found this Thyoue " very abundant." They were " collected from rocks in two 

 feet of water (at half tide), near ' muello ' of Grace & Co., on the bay called ' Inde- 

 pendencia ' (this little bay to be distinguished from the great bay of ' Indepeu- 

 dencia ' on the coast, south of Pisco)-" The color of these specimens in life is 

 noted as "black." It may be added that the nearest relative of this species ap- 

 pears to be Thyone bwccalis Stimpson of Australia. 



