REPORT ON THE TETRACTINELLIDA. 
437 
lie included several not very closely connected sponges, and of these, two in particular, 
evidently of different generic value, have been made the subject of controversy. These are 
Tethya cranium and Tethya lyncurium. For one of these it became necessary to create 
a new genus ; and it is claimed by Gray and Carter that the first to recognise this was 
Nardo, who in 1833 proposed the genus Donatia to receive Tethya lyncurium ; and if 
the genus Donatia were so contrived as to cut Tethya lyncurium adrift from Tethya 
cranium, the contention would of course be successful. Neither Nardo’s definition, 
however, nor the species which he enumerates in illustration, bear out this supposition. 
The definition runs as follows : — “ Donatia, aggregata tuherosa, rigida, tenacia, fere 
pumicosa in sicco, sarcoidea ponderosa in vivo, superficie varia, ssepe porosa, fulcimenta 
aculeiformia conspicua, rigida, simplicia vel polycuspidata quandoque granulosa in 
aggregatorum superficie, dispositione varia, pulpse animalis ope coalita. Species : 
Donatia lyncurium N. , cydonium N. ; cuspidaria N. ; ohvolvens N. ; longaculea 
N.,” &c. 
There is nothing in this piece of latinity exclusive of Tethya cranium, and as to the 
other species, all that we know of “ cydonium ” points to its Geodine character. Donatia 
may be regarded as a mere synonym of Tethya ; nor could we expect much better when 
we call to mind that Nardo divided all sponges into three orders, including between them 
altogether not more than twelve or fourteen genera. Had Nardo not found a friendly 
exponent in Schmidt, his generic names would probably have all long ago been forgotten. 
The exclusion of Tethya cranium we owe to 0. Schmidt (1862) ; the revised defini- 
tion of the genus for which he retained the name Tethya is as follows : — Tethya, Lamarck ; 
corticatse glohosse vel subglohosse, cute cra.ssa, fihrillis distincte contexta et corpuscula 
stellata continuente ohductse. Spicula simplicia fiasciculata e centro vel e nucleo sub- 
centrali radiantia usque ad superficiem. 
By this definition and the citation of Tethya lyncurium as an instance, Schmidt has 
stamped the name Tethya upon Tethya^ lyncurium indelibly, and thus the “ orange of 
the sea,” as Lamouroux called it, will now always be known as Tethya lyncurium, Linn. 
For Tethya cranium, Schmidt proposed the new name Craniella cranium. An attempt 
to reverse this nomenclature was made five years later by Gray, who retained the name 
Tethya for Tethya cranium, and coined a fresh designation, Donatia aurantium, for 
Tethya lyncurium. The proposal was made too late, and would lead to much incon- 
venience ; had it been suggested before Schmidt’s restricted definition of Tethya was 
published, the name Donatia would probably have found wider acceptance ; now it 
naturally meets with no support, always with the important exception of Carter’s 
ingenious advocacy. 
The variations of this, as of most well-known sponges, are so extreme, that it 
would need a laborious examination of a large series of specimens to define the limits 
of individual and collective differences. 0. Schmidt at first (1862) recognised two 
