250 Transactions. 
Fam. SYNTHECIDAE. 
Synthecium orthogonium (Busk). 
Sertularia orthogonia Busk, 1852, p. 390: Bale, 1884, p. 38. 
Synthecium orthogonia Bale, 1888, р. 767. 
Synthecium orthogonium Jäderholm, 1903, p. 289; 1916, p. 6: Billard, 1910, 
p. 23: Bale, 19145, p. 6. 
Synthecium campylocarpum Allman, 1888, p. 78: Marktanner-Turneretscher, 
1890, p. 248: Campenhausen, 1897, p. 310: Farquhar, 1897, p. 466: Billard, 
1910, p. 26: Jäderholm, 1916, p. 6. 
? Synthecium campylocarpum Inaba, 1890-92, figs. 52-54 : Stechow, 1913, p. 127: 
Jäderholm, 1919, p. 14. 
I unite Allman's S. campylocarpum with Busk's species, as I am quite 
Museum Hydroida, refers to the types of the two species, and says nothing 
as to their relationship. He mentions, however, that Busk’s type exhibits 
the right-angled outward prolongation of hydrotheca as shown in his sketch, 
copied in my Catalogue 
I conclude that these observers regard the abrupt curve outward of 
hydrotheca and its horizontal continuation as characteristic of S. ortho- 
дотит. The distinction fails, however, owing to the great variability of 
the hydrothecae in this particular. On the same branch one often finds 
hydrothecae bent out abruptly, as in Busk's figure, while in others the 
curvature is quite gradual. Even in the fragment of Allman's species sent 
to me one or two hydrothecae are quite similar in this respect to Busk's 
: ; 
Allman, I found on on 
something like those described by Allman as occurring in S. elegans, but 
with the markings more irregular. They are not more than one-third the 
length of the ordinary ones, and of about the same width. Whether thcse 
are the male form or are abnormal is at present doubtful. 
The Japanese form figured by Inaba, Stechow, and Jäderholm does 
occurring to a much less extent in S. patulum. 
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