260 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
The specimens were prepared by the Tullberg (91) method, which 
consists in stupefaction by the gradual introduction of magnesic sulphate 
into the water containing the actinians, and in subsequent hardening by 
means of chromic acid. This method, when properly employed, yields 
beautifully expanded and thoroughly hardened specimens, and my expe- 
rience with it has been such that I can fully indorse the recommendations 
given it by Tullberg (91), Carlgren (93, p. 7), and others. Speci- 
mens prepared in this way were cut transversely with a common razor, 
and the number and arrangement of the mesenteries and siphonoglyphs ! 
were recorded. Owing to the large size of the specimens, this could be 
easily done under the magnification of an ordinary hand lens. 
Siphonoglyphs. — The Hexactinia, to which Metridium belongs, were 
until recently supposed to possess always two siphonoglyphs; but this 
surmise has been shown to be not well grounded, and, in, the species 
under consideration, as MeMurrich (91, p. 131) has already pointed 
out, either one or two siphonoglyphs may be present. Iu the 131 
specimens that I examined, 77 (or about 59 per cont) had only one 
siphonoglyph (Fig. 3), 53 (or about 41 per cent) had two siphonoglyphs 
(Fig. 1), and a single specimen possessed three such organs (Fig. 6). In 
no instance was a specimen found without a siphonoglyph. ‘The smooth 
surface of the siphonoglyph is so strongly contrasted with the longitu- 
dinally ribbed surface of the rest of the oesophagus that in none of the 
specimens examined was there any uncertainty as to the number of 
siphonoglyphs present. The striking difference between these two kinds 
of surface cannot be made to appear so clearly in tho figures as it did 
in the actual specimen, where, in addition to tho cut face, the natural face 
of the esophagus could also be inspected. MeMurrich (QUIS De lol) 
remarks that in the individuals examined by him, those with one sipho 
noglyph were almost, if not quite, as frequent in oceurrence as tho 
with two, but in my enumeration it will be seen that they were really 
somewhat more numerous. 
Since only one of the 131 specimens possessed three siphonoglyphs, it 
1 The term “ siphonoglyphe " was first introduced into zoólogical nomenclature 
by Hickson ('84, p. 694), and has since been widely accepted. Professor Hickson 
kindly informs me that the last syllable of this term is derived from the Greck 
word yAvgts, which in the plural form, yAvoí8es, has been used to signify the grooves 
on an arrow for the insertion of the feathers. The root of this word appears to 
call for no final e, and since in making English words it is best, as Professor 
Hickson remarks, to use only roots, I therefore propose to change the spelling 
of the term in question by omitting the final e, and to this Professor Hickson 
assents. 
