314 Miscellaneous, 



of short tentacles, and exhibits upon its surface a number of trans- 

 verse rows of pointed hooks ; it is a prehensile organ employed by 

 the animal to capture its prey ; but it also serves, thanks to its 

 hooks, for the locomotion of the two commensals, for M. Jousseaume 

 has seen it protruded by the worm and applied to the bottom, as if 

 to find a point of support, and then contracted so as to drag the 

 polyp along. The shields are two in number, as in all the species 

 of the genus Aspidosiphon : the first is grooved with transverse 

 striatious in front and longitudinal striations behind, and is situated 

 at the base of the proboscis, near the anus ; the second occupies the 

 posterior extremity of the worm, and is circular in shape, with 

 radial grooves. I know not what is the role of this latter, but the 

 anal shield closes the orifice of the tube when the animal is retracted, 

 and consequently acts as a defensive operculum. 



These worms belong to two new species, one of which inhabits 

 Heteropsammia and the other Hetci-oqiatJius. The former greatly 

 resembles Aspidosiplion mirabilis, Theel, from the Swedish seas, but 

 differs from it by reason of its habitat, in the shape of its nephridia, 

 and in the number of the coils in its digestive tract ; the latter is allied 

 to a Malayan species, Aspidosiplion ravus, Sluiter, from which it is 

 readily distinguished by the grooves in its shields. Since Deshayes 

 has proposed for the Gastropods which he believed to be commensal 

 with the two polyps the names Cryptohia heteropsammiarum and 

 C. Michelini, it will be well to designate the Gephyrean of Hetero- 

 psammia Aspidosiplion heteropsammiarum, and that of Heterocyatlms 

 A. Michelini. 



The commensalism of the Aspidosiphon is complicated, at least in 

 the case of A. Michelini, by the presence of the young of a very 

 small Lamellibranch moUusk (Kdlia Deshayesi, Jousseaume, sp. n.), 

 which takes up its abode in the cavity inhabited by the worm, and 

 shelters itself in the depressions in the surface of the latter ; when 

 the commensals are adult the number of these bivalves amounts to 

 about a dozen. They derive their sustenance from the current of 

 water which passes into the interior of the spiral cavity thi'ough 

 the linear perforations of the polyps. 



We may sum up our results as follows: — (1) The commensal of 

 Heteropsamraia and Heterocyatlms is a worm of the genus Aspido- 

 siphon, and not a Gastropod ; (2) each polyp has its particular 

 species, and develops concurrentlj- with it ; (3) the polyps attach 

 themselves to various shells, and not to those of a distinct genus ; 

 (4) the rugose tube by which the shells are continued does not 

 belong to their substance, but is formed by the worm ; (5) the 

 association of the worm and the polyp is complicated, at least in 

 the case of Heterocyatlms, by the presence of a third commensal in 

 the shape of a bivalve moUusk. 



Setting aside this latter animal, the commensalism of Aspido- 

 siphon with the polyps reminds us in every respect of that of Para- 

 pagurns pilosimanus with the colonies of Epizoanthus. — Comptes 

 Bendus, t. cxix. no. 1 (July 2, 1894), pp. 96-98. 



