364 JOHN F. FULTON, JR. 



found in representatives of oxoiy class of mollusc save the 

 Ainpliineura/ and it is also common among the crustaceans 

 and the arachnids. Kecently the chemical and physiological 

 properties of haemocyanin have been extensively investigated 

 by Alsberg and Clark (1914), who find that the pigment lacks 

 many of the remarkable properties of haemoglobin ; particu- 

 larly to be noted is its small binding power for oxygen. 



Pinna glob in. —The blood of the lamellibranch Pinna 

 squamosa is distinguished by a respiratory pigment which 

 contains manganese. This metal is linked to a protein which 

 contains the usual elements of blood pigments, viz. C, H, N, 

 S and O2, and these in proportions similar to the corresponding 

 elements of haemoglobin (Griffiths, 1897). 



Haemoglobin. — The colour of the 'blood-clam' (Area) 

 is due to the presence of haemoglobin in the blood ; the 

 pigment is found also in other Lamellibranchs : Solen 

 legumen, and Cardita, and in the gastropod Planorbis 

 (Lankester, 1872; Leitch, 1910). 



Chlorophyll has been detected in many of the Mollusca. 

 The colour of the green oyster is due to an algal infection 

 (Lankester, 1880). Enterochlorophyll has been described by 

 MacMunn (1883 c, 1885 fc) as existing in the liver of many 

 crustaceans and molluscs. For further discussion of entero- 

 chlorophyll, see below% p. 309. 



4. The Annelida. 



One of the most interesting characteristics of the coloration 

 in annelids is the fact that the coloured substances found in 

 this phylum are usually respiratory pigments ; few of the 

 coloured substances serve alone for ornament. The segmented 

 worms have two circulatory fluids : the perivisceral (coelomic) 



^ The chitons possess a non-metallic respiratory pigment, ,9-achroglobin, 

 which was described by Griffiths (1897). In addition to this pigment 

 a yellow lipochrome is present in the blood, which is more common in the 

 female of the species than in the male, and is thus responsible for the 

 deep yellow colour which the female chiton assumes during periods of 

 reproduction. 



