54 



science has not arrived at sufficient accuracy to make any 

 system of families of much value, especially as naturalists are 

 so divided on the subject, and none are generally received. I 

 include the genus Siphonaria in my observations, only be- 

 ca.use they have limpet shells, and their habits of life being 

 entirely similar they are generally mistaken for true Patel- 

 lidae. They are widely distinct in their anatomy, organs 

 of respiration, digestion, dentition, vision, touch, etc. But 

 they are found on our rocks just as limpets are, and in the 

 midst of them and externally cannot be distinguished from 

 them. They are very common. Two species have been ex- 

 amined by me, and a third is said to occur, but I liave not 

 been able to find it. Four or five are known in A.ustralia, but 

 the number is not very clearly ascertained, nor will it be until 

 the animals have received more attention than they have met 

 ■with from Australian naturalists. 



Siphonaria denticulata. Q. and G., Toy. Astrol., Vol. 2, 

 p. 340, fl. 25, f. 19 and 20, var. Tasmanica, mihi. 



Shell, irregularly oval, with protuberance on the siphonal 

 side, tumidly conical, high, apex median, subacute ; with 40 

 to 50 fine, flattened and diminishing ribs ; ribs interrupted by 

 a sinus at the siphonal side ; color, bluish white, apical area 

 brown or olive, lines of growth olive, giving the shell a zoned 

 appearance, but varying in every individual shell ; often 

 stained an uniform bluish black or much corroded ; interior 

 rich purple brown, highly enamelled ; edge crenulate, spatula 

 brownish white, extending partly down siphonal sinus. 



Animal, dull brown, with numerous small light spots of 

 varying size ; foot yellowish, shading to orange near the head ; 

 mantle, brown, fringed at the edge with whitish and black 

 spots. When the mantle is irritated the black spots seem to 

 be the points where it is drawn in. Head, a large and many 

 lobed mass, forming a cup-like expansion round the very small 

 mouth ; no eyes visible, and though they are represented in 

 Messrs. Quoy and Gaimard's figures of S. diemenensis, I have 

 never been able to detect anything, but a single black dot of 

 varying position on one of the lobes of the head. Above the 

 foot on the left side of the animal is a lobe which forms a 

 kind of semicircular tube, closely pressed to the shell, and 

 here the mantle is not visible. This tube is the siphon, aad 

 is lobed so as to be capable of a kind of bipartition which 

 probably divides the orifice into an excretory as well as res- 

 piratory duet. This lobe of the foot acts as a kind of 

 operculum, closing the orifice when necessary. My belief is 

 that the animal breathes both air and water. If placed in the 

 open air the siphon tube opens at once, and the tube is always 

 open when the animal is taken from the rocks which it in- 

 habits, and which are not long covered by the tide. On 



