DIPLURA. 319 



"EuDEiN'DUIUM rVLSILLUM," SrOS. 



Among provisional species must be here included a hydroid described by Sars, in his 

 ' Middelhavet's Littoral-Fauna,' p. 45, tab. i, figs. 14 — 10, under the name of " Eiulcndrmn. 

 pnsillimi." It is certainly, however, not a Eudendriicm, and is probably cither a Bouijainvillia or 

 a Perigonimus. The gonosome has not been observed, and though Sars gives a very full descrip- 

 tion of the trophosome, it is impossible, without a knowledge of the gonosome, to assign the 

 hydroid to its proper genus. 



The following is Sars's diagnosis : — 



" Eudetidrium pusilluiii. Sm-culis e tubulo repente filiformi ramoso lajvi erectis humilibus, 

 annulatis, hyalinis; ramis paucis (3 — 4), sparsis, brevibus, crassis, flexuosis seu tortis, annulatis, 

 simplicibus aut dichotomis, apice instar tubae aliquantum dilatato et a corpore seu capitulo 

 animalis distante ; capitulo aniuialium elongato, subcylindrico, non retractili, albo, tentaculis 

 circiter 20 uniserialibus." 



The species was found in the neighbourhood of Messina, tolerably abundantly growing a 

 little below the surface of the sea on a brownish-red seaweed. It is quite a small form, attaining 

 a height of only an eighth of an inch. The hydranths manifestly belong to the BojyainviUia or 

 Pcrlffonimus type, and not .at all to that of Eudendriinn. Sars's description is accompanied by some 

 good figures of the trophosome. 



DIPLUEA, Green, in Lit. 



Name. — From cittAoc, double, and oupa, a tail ; in allusion to the two tentacles, which are 

 developed like a tail from one of the marginal bulbs of the planoblast. 



CoRYNE, — Sleenstrup. 

 Steenstrupia, — Agassi: . 



TROPHOSOME. — Htdkophtton solitary, rooted by a filiform hydeorhiza, and 

 surmounted by a claviform iitdeanth.' 



GONOSOME. — Planoblasts springing from the body of the liydrantli at the 

 proximal side of the tentacles. Umbrella deep bell-shaped ; manubrium with simple 

 or quadrilobate mouth ; radiating canals terminating each in a marginal bulb, one of 

 which, in the mature medusa, carries a pair of filiform tentacles, the others being 

 destitute of tentacles. 



^ For the description here given of the trophosome I have no data beyond the figure which 

 accompanies Steenstrup's memoir ; and as this figure is evidently a mere sketch, and plainly inexact 

 in its details, the above diagnosis founded on it is necessarily incomplete. Prof. Steenstrup's original 

 specimens have unfortunately been lost, and we do not possess data suflScient for the determination of 

 even the family to which Diplura ought to be referred. Its allocation to the BougainviUidce must, 

 therefore, be accepted with reservation. 



