Qcipers^ Piddocks^ and Ship-worms 177 



granulations are arranged in irregular concentric lines. 

 Ossicle half-moon shaped. It is a local species, but 

 not conhned to any particular stretch of our shores. 

 It appears to range from a depth of 5 to about 35 

 fathoms, hiding in old shells and rock crevices. 

 Occasionally at extreme low water it may be found 

 nestling among tufts of Corallina. 



The Skye Gaper (Poromya granulata) is a fragile 

 little pearly shell, with almost equal valves, of 

 rhomboidal form, gaping behind ; the right valve 

 overlapping the left. It is ornamented by minute 

 and rather crowded granulations, and dusky coloured, 

 with traces of the brown epidermis at the edges only. 

 Hinge-plate thickened, bearing in the right valve an 

 erect thick cardinal, in the left a small triangular 

 cardinal and a plate-like lateral behind. There is no 

 ossicle. The animal is cream coloured, with a lonof, 

 slender, transparent foot. The siphons are short 

 and thick, encircled at their base by about 20 long 

 filaments which curve back over the shell. It is 

 found in mud on rocky shores in Skye, at a depth 

 of about 40 fatlioms. This little mollusk has the 

 distinction, not only of being the only native repre- 

 sentative of its genus and family, but also of its 

 Natural Order, the Septibranchiata, which is dis- 

 tinguished from the other orders by the gills being 

 replaced by a muscular partition {septum), which 

 reaches from the first adductor muscle to the siphons. 



