422 .f. f! HA HAM KKKi;. 



illustrate the appearance of the skin of a Lepi do siren of 

 the stage mentioned during the da}' and during the night. 

 The night specimen had been exposed to faint lamp-light for 

 several minutes, and consequently the retraction of the 

 pseudopodia is not quite complete. 



From fig. 4 it will be seen that the black chromatophores 

 tend tOAvards two distinct types, differing in the appearance 

 of the contained pigment and in the degree of ramification of 

 the pseudopodia. 



In type A, which is the less numerous, the pigment is very 

 black, the cell body is compact, and the pseudopodia are 

 long and comparatively slightly branched, and often present 

 a varicose appearance. In type B the contained pigment is 

 less opaque, of a brownish colour, and the cell body is often 

 very irregular in shape, ]n-ojecting in great trunks from 

 which arise numerous short and very irregular pseudopodia. 



Of these type B appears to be the more highly sensitive to 

 liy-ht, a much fainter amount of light suthcing to cause 

 extrusion of its pseudopodia. 



AVhen in a state of maxinuim expansion the pseudopodia 

 frequently anastomose both with their neighbours and with 

 those of other chromatophores. i^nastomosis often takes 

 ])lace between pseudopodia belonging to chromato])hores of 

 the two different types. This, together with the presence of 

 intermediate forms, indicates that the two types- are not 

 really distinct, but arc merely tlie exti'enies of \aviatiou of a 

 single tyi>e. 



It is instructive lo compare vertical sections through the 

 skin in diffei-ent light conditions. Fig. o illusti-ates such 

 sections from (1) a young Ijcpidosi riMi of Stage 88, killed 

 at 9 p.m., l)y faint lamp-light (fig. .")(•), (2) one of the same 

 brood taken from det-p sliade at 2 p.m. (tig. 5 h), and 

 (8) a rather younger Lepidosireii taken from an opcMi 

 white enamelled dish witli clear water and e\|iose(l to l)riglit 

 dilfiised daylight (fig. 5 a). 



In (1) the chi'oniato])lioi'i's are in tlieir state of niaximnni 

 cont ract ion, and I niav mention that the scattered clu'omato- 



