NORTH AMEPJCAN PORIFER.E. PART I. 407 



JANTHELLID^. 



This group was first described by Dr. J. Edward Gray in 1869 in the Proceedings of the 

 Zoological Society of London. The specimen, of which a description is given below, and 

 Gray's own description, shows that the group has really a ftimily value as he supjiosed. 



The fibres are of enormous size when compared with those of the preceding group, and 

 are destitute of the yellowish filling found in the Dendrospongiadne and Aplysinidse. 

 Though typically hollow they are in part often sohdly filled by the concentric layers of horny 

 material. The exterior of these fibres is coarsely granular, and they are very opaque. The 

 aspect of the di'ied specimens, as described by Gray, is very characteristic. Instead of being 

 massive the}'^ are frondose. The sarcode, as in the Aplysinidte, shrinks down closely upon 

 the flattened trellis work of the skeleton and covers the huge fibres with a thin tenacious 

 coating, which spreads across the broad interstices or mesh of the fibres, and is here and 

 there pierced by canals which pass entirely through it. Gray describes the stem, " root, " 

 as composed of interlaced filaments from which the fibres of the frond spread out in all 

 directions. All of the species which he desci-ibes, viz., Jantliella jlahelliformis, bastn, and 

 Jlomei, seem to have been either flat, as in Gorgonia, or modified into a funnel shape ; 

 the fibres also were smooth apparently. It will be seen below that Jantliella concentrica 

 differs very much and can only be provisionally referred to the same genus. 



Janthella. 

 Janthella concentrica Hyatt. 



The description of Janthella Homei Gray applies very well to this specimen, but as there 

 is no positive notice of the most prominent characteristics of this species I must consider it 

 a new form. The fibres are of enormous size, being from one to three mm. in diameter. The 

 youngest or the outer portions are smgle, but the inner branches are compound and orna- 

 mented with thick, short spines and more minute wart-like prominences. The compound 

 fibres are made by the frequent tendency of the fibres to divide into branches which 

 run side by side for long distances before they separate. As a result of this, and the 

 freedom with which keratose matter is deposited, we find the fibres almost always double, 

 or when joined by other branches, still more numerous, though contained within common 

 layers of horny material and externally appearing as but one stem. The spines are, also, 

 in reality only the terminations of abortive branches which run parallel with the fibres 

 from which they sprang, and are closely united with them for a short distance but have free 

 tips which j^rotrude out of the common covering like the end of a young thorn. The 

 type specimen is in the Collection of the Museum of Comparative Zoology, and is only a 

 fragment, but it shows that the sponge must have been very irregularly frondose. The 

 mesh is also quite irregular in size and shape, varying from 11.6 mm. to only 5 mm. in 

 length, while the breadth varies from 3 to 6 mm. The specimen appears under the name 

 of Antlpathes Jlahelliformis, but whether the same as Dana's type or not I have no means 

 of determining. 



Fejee Islands. U. S. Ex. Expedition. 



