SCAPHOPODA. 



349 



Fam. 23. Teredinidae. The branchiae are to a large extent contained in 

 the branchial siphon. Siphonal region vermiform, provided behind with two 

 accessory shell-pieces. Shell very small, covering only anterior part of animal. 

 Teredo L., T. navalis L. (Fig. 271), shipworm, was the cause of the famous 

 dam-break in Holland at the beginning of last century. ^^/ 



Sub-order 7. ANATINACEA. 



Hermaphrodite ; ovary and testis with separate orifices ; external gill directed 

 dorsally, and without the reflected (outer) lamella. 



Fam. 24. Pandoridae. Foot tongue - shaped, without 

 byssus. Siphons very short. Pandora Bruguiere ; Myo- 

 chama Stutchbury. 



Fam. 25. Lyonsiidae. Foot cylindrical, byssiferous ; 

 siphons short. Lyonsia Sturton ; Lyonsiella Sars. 



Fam. 26. Anatinidae. Foot slender, without byssws ; 

 siphons long ; a fourth pallial orifice. Anatina Lam. ; 

 Thracia Blainville ; Pholadomya Sowerby. 



Fam 27. Clavagellidae. Foot reduced, without byssus ; 

 siphons long, united ; valves continued by a calcareous 

 tube secreted by the siphons. Clavagella Lam. ; Asper- 

 gillum Lam. (Fig. 272). 



Order 5. SEPTIBRANCHIATA. 



With branchial septum. 



There are three pallial fusions, two siphons more or 

 less elongated, and two adductors. The gills (Fig. 264 D) 

 have the form of a muscular septum, extending from the 

 anterior adductor to the junction of the two siphons and 

 surrounding the foot, with which it is continuous. This 

 septum presents symmetrical orifices. 



Fam. 1. Poromyidae. Siphons short ; foot elongated. 

 On each half of the septum there are several groups of lamellae separated by 

 orifices. Palps well developed. Hermaphrodite. Poromya Forbes ; Silenia 

 Smith. 



Fam. 2. Cuspidariidae. Siphons elongated, united; foot reduced; palps 

 reduced or absent; branchial septum pierced by isolated symmetrical orifices; 

 sexes separate. Cuspidaria Nardo. 



The genus Entovalva Voeltzkow, is not well enough known for its affinities to be- 

 determined. The mantle has a posterior orifice ; the foot is large, with a posterior 

 sucker. There is an hermaphrodite gland. It inhabits the oesophagus of a 

 Holothurian from Madagascar. 



FIG. 272. Shell of 



Aspergillutn javanum 

 (after Adams). 



Class II. SCAPHOPODA* (SOLENOCONCHAE). 



Dioecious Molhisca without eyes or heart. The edges of the mantle 

 are fused to form a tube which is open before and behind, and secretes- 

 a tubular calcareous shell. 



* Lacaze Duthiers, "Histoire de 1'organisation et du developpement du 

 Dentale," Ann. Sc. Nat. 1856-58. Plate, "Ueb. d. Ban u. d. Verwandt. d. 

 Solenoconchen," Zool. Jahrb. f. Morph. Bd. 5, 1892. Kowalewsky, "Etudes sur 

 1'Embryogenie du Dentale," Ann. du Mus. de Marseille, t. 1, 1883. 



