948 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
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supporting a bivalve operculum, the structure of which is so delicate as to be hard to decipher, the f. 
appearance being that of the operculum of the genus Stegopoma. * | 
Gonosome. — Not known. 
Distribution. — Station 3859, between the islands of Molokai and Maui, 138 fathoms. 
It is likely that a separate genus should be instituted for this species and Cryptolaria geniculata a 
Allman a, both of which differ from all other known members of the genus in having a well-marked j; 
operculum. 
Family SERTULARID4E. 6 
Trophosome. — Hydranths with a conical proboscis. Hj’dro thecae sessile, adnate, or partly || 
embedded in the hydrocaulus, arranged definitely in more than a single row. An operculum of less | 
than five parts almost always present. Nematophores wanting. 
Gonosome. — Gonophores always inclosed in gonangia and never producing medusoid forms. 
Genus SERTULARIA. 
Trophosome. — Hydrothecae in opposite or subopposite pairs, each pair being normally borne on a 
separate internode of the hydrocaulus. Operculum normally of two flaps. 
Gonosome. — Gonangia oval or ovate, with, a short collar and' broad aperture, and no internal I 
marsupium. 
Sertularia snyderi Nutting, new species. 
(PI. iv, fig. 5; pi. x, fig. 15.) 
Trophosome. — Colony unbranched, attaining a height of about one-third of an inch. Stem simple, j: 
straight, slender, with nodes obscure or absent, but when evident about midway between the pairs of 
hydrothecie. Hydrothecse exceedingly slender, strictly opposite, but borne on front of stem, somewhat 
pistol-shaped, the butt of the pistol representing the proximal portion of the hydrotheca, the inner 
side of which is contiguous with its fellow, the distal three-fourths being free and bent outward nearly 
at a right angle with the stem. Aperture with two large opposite teeth and a minute superior tooth.) 
Operculum very delicate, but apparently of two valves. 
Gonosome. — Not known. 
Locality. — Station 3939, northwest of the island of Laysan, 163 fathoms. 
This species has the most slender hydrothecie that I have seen in the genus. It was found growing I 
as a parasite on a plumularian hydroid'. 
Genus SERTULARELLA. 
Trophosome. — Hydrothecae biserial, strictly alternate, with an operculum almost always composed 
of 3 or 4 strong triangular segments. 
Gonosome. — Gonangia usually ornamented with annular ridges or corrugations. Aperture at the 
end of a trumpet-shaped tube, or else surrounded by blunt spines or nodules. 
Sertularella lata (Bale). 
Distribution. — Station 3848, south coast of the island of Molokai, 44 fathoms; station 3854, south 
coast of the island of Molokai, 134 fathoms. 
Thuiaria lata Bale, Catalogue of the Australian Hydroid Zoophytes, 129, 1884. 
Sertularella dentifera Torrey. 
(PI. xi, fig. 1.) 
Gonosome. — (Hitherto undescribed. ) Gonangia ovate, strongly annulated throughout, and with j 
a very small tubular neck around which a collar arises. 
a Challenger Report, The Hydroida, Part II, p. 41, 1888. 
i>The classification of genera in this family and in the Plumularidse is the same as that adopted in the author’s 
monograph, "American Hydroids,” Parts I and II, published by the U. S. National Museum as Special Bulletin No. 4. The 
definitions used in the present work are somewhat abridged, but practically the same. 
