32G PERIGONIMUS VESTITUS. 



GONOSOME, — GoNOPiiORES developed from tlie hydrorliiza ; medusa thimble- 

 shaped, with two marginal bulbs which carry long tentacles, and alternate with two 

 smaller bulbs destitute of tentacles ; manubrium with the oral margin four-lobed. 



Colour of hydranths white. 



Habitat. — On a shell inhaljited by a hermit-crab. 



Locality.— Y\x\\\ of Forth, Dr. Wright. 



I have never met with this remarkable little hydroid. " When first observed," says Dr. 

 Wright, " its closely set and dense white polypes, surrounded Ijy their gelatinous envelopes, were 

 mistaken for a mass of minute ova." 



G. Perigonimus VESTITUS, Allmaii. 



Plate XI, figs. 1—3. 



Perigonimus vestitus, — Allman, in Ann. Nat. Hist, for July, 18G4. Hindis, Biit. Hydr. 



Zoopli., p. 94-. 



TROPHOSOME. — Hydkoc.a.ulus consisting of numerous stems rising at short 

 intervals from a reticulated stolon, and attaining a height of from half a line to two 

 lines, becoming greatly dilated towards the summits where they pass uninterruptedly 

 into the body of the hydranths, mostly simple, but occasionally with one or two 

 short lateral branches ; peuisakc coarse, roughened by adherent particles of sand. 

 Hydranths with from six to ten tentacles, which are rendered hispid by minute 

 clusters of thread-cells, and are lield straight in extension with the alternate cues 

 elevated and depressed ; posterior part of the body invested by the rough perisarc, 

 which is thence continued as a delicate, smooth membrane over tlie remainder of the 

 body nearly as far as the mouth. 



GONOSOME. — GoNOPHORES elevated on long peduncles, which spring from the 

 hydrocaulus, and occasionally also from the hydrorhiza, the peduncle for about its 

 proximal half covered by a continuation of the chitinous perisarc. Medusa, at the 

 time of liberation, oviform, the cavity of the umbrella being very dee]) and the 

 codonostome much contracted; umbrella-waUs very thin, and with numerous scattered 

 thread-cells immersed in them, two opposite marginal tentacles, and two intermediate 

 marginal bulbs destitute of tentacles, manubrium with four shallow lii:is. 



