158 



BREATHTNC} OF AMPULLARIA 



on l)eiiig submitted to the same test, showed tliat tlie truncated 



part alone was permeable by air. 



Fischer and Bouvier have made some interesting observations 



on the breathing of a species of Amjndlaria (insularvm Orl».j. 



Tlie species has, in common with all Amjmllaria, two si])hons, 



but while the right siphon is but sliglitly developed, the left is 



very long, almost twice as long as the 

 shell (see Fig. Go). The animal, when 

 under the water, lengthens its siphon, 

 brings the orifice to the surface, and l<y 

 alternatelyraising and depressing its head 

 produces in the pulmonary sac movements 

 of ex- and inspiration ; these are repeated 

 about ten or fifteen times at regular 

 intervals of from six to eiglit seconds, 

 a method (.)f respiration strongly resem- 

 bling that of the (Jetacea. At the same 

 time, liranchial respiration takes place. 

 If powdered carmine is added to water, 

 the particles are seen to enter tbe l»ran- 



Vic. 65.-Ampullaria insul- ^.j^-^| ^^^ . ^^^^ i^uAlOlX and paSS out 



artdii Orb. : A, bivatliiiij,' . . 



water; B, Iji-eathing air; Si, l)y the short rigllt siplioll. Sometimes 



siplion ; T, iiii))er : /, lower 4,1 • i • 1 . ,- 



tentacles; x'palliul ex-^he animal remains under water ior 

 pansion, performing tlie part hours without rising to the Surface to 



of e.xcurrent siplion. (Alter 



Fisclier auil Bouvier, x J.). 



inspire air. In I'alrata (Fig. OG) the 

 liranchia is very large, and projects like 

 a leaf or fan al)ove tlie shell on the left side ; on the correspond- 

 ing position on the rigiit side is a, long filiform appeiulage, wliich 

 some have regarded as representing the other Ijranchia. 



02)isthohra)ifhiata. — A true In'anchia occurs only in the Tecti- 

 1)ranchiata and the Ascoglossa. It lies on the right side, and is 

 usually more or less external, being partly covered sometimes by 

 the shell (as in UmhreUa, Fig. 5), sometimes Ity a fold of the 

 mantle. In the Pteropoda (which are probably derived from the 

 Tectibrancliiata), all the Thecosomata, with tlie exception of 

 Cavolinia, have no specialised l)rancliia, but probal)ly respire 

 tbrougli portions or the whole of the integument. In the 

 (rymnosomata an accessory branchia has in many cases Ijeen de- 

 veloped at the posterior end of the body. Fncvmodennon alone 

 lias both lateral and posterior l)ranchiae well developed, Clione 



