124 The Ottawa Naturalist [Dec. 



which are rudimentary colored visual organs on the five ocular 

 plates, alternating with the five genital plates round the peri- 

 proctal space at the aboral pole, did not show any pigment. 

 It was a perfect albino, and, so far as I have been able to ascer- 

 tain, the first albino sea-urchin ever seen. It was a beautiful 

 object, appearing as though its characteristic apple-shaped form 

 were delicately carved in white marble. It is now conspicuous 

 in the faunal collection of fishes and invertebrates at the 

 Dominion Biological Station, St. Andrews, N.B. 



An interesting albino specimen of the lobster (Homarus 

 americanus), from the Pictou shore, Nova Scotia, came into 

 my possession some time ago. Pale tinted specimens of lobsters 

 have long been known, some of which, in place of the dark 

 blackish blue of the usual type, show reddish or yellowish 

 coloration ; but the specimen which I secured was dappled all 

 over with irregular patches of vellowish white and the blue- 

 black color was confined to small, irregular spots, chiefly on the 

 upper parts of the tergum, or dorsal portion of the body and 

 tail-segments. This very unusual specimen was only 8 inches 

 in length and cannot have been more than three or four years 

 old. It might be suggested that, instead of being an albino, 

 the specimen merely retained some of the varied coloration of 

 the infantile stages, for when half-an-inch long, at the stage 

 when salts of lime and pigment first appear in the delicate 

 shell, the general color is maroon, or sometimes pale brown with 

 green intermingled, and especially prominent are some chalk- 

 white spots, four or five in number, apparently marking the 

 attachments of the tendons of the cephalo-thoracic muscles 

 inside. These spots are even more distinct at the sixth stage, 

 about the fifth week after hatching, when its length is three- 

 fifths of an inch. At the seventh stage (seventh week), when 

 three-quarters of an inch in length, a definite pigment layer 

 appears below the external cuticle. In the adult lobster this 

 pigment layer, called by Dr. W. B. Carpenter the areolar layer, 

 is a canaliculated stratum crowded with lime salts, and is 

 hypodermic in origin, and mainly constitutes the thick, dense 

 shell. A tubular laver occurs beneath, likened by some authori- 

 ties to dentine, being thick and dense, and forming the gleaming 

 white part which is seen when the shell is broken. Lowest of 

 all is a thin lamellar non-calcified layer. The color in the 

 areolar layer is due to chromogens, which are converted by 

 boiling, dehydration by alcohol, etc., and even by exposure to 

 excessive light, into a red lipochrome. Every one is familiar 

 with the change, by boiling, of a dark blue or blackish-green 

 lobster into a bright scarlet one. The normal prevailing color 

 of lobsters on the Atlantic coast is blackish-blue, sometimes of 



