656 MR JAMES MURRAY ON 



[islandicus]) ; second, the hastatus type, which is round or oval, with the surface 

 studded with rods, which are imbedded in a clear matrix, a form of egg-covering similar 

 to that of many winter eggs of Rotifers and other animals ; third, the antarcticus type, 

 which is oval, without spines, viscous, and is laid free. 



The eggs of M . hastatus, the only British species of the group which has the spines 

 imbedded in a hyaline matrix, though it lays its eggs free from the moulted skin, yet 

 has been found to deposit them three together in the cast skins of certain Cladocera so 

 constantly that this seems to be a normal provision for their safety. Another species, 

 M. annulatus, which lays smooth eggs in the skin, carries this skin about with it, like 

 a sack on its back, till the eggs are hatched. Living young have been seen in the 

 body of one species, M. zetlandicus ; but as this species constantly lays eggs in the 

 skin, we must suppose the living young to be the result of some mischance in develop- 

 ment, such as inability to deposit the eggs, which would then hatch in the body. 



Moulting. — Eggs of the macronyx type are usually all laid before the parent begins 

 to emerge from the skin, though of course the old skin has been completely loosened 

 before the eggs are laid. The animal in its new skin has room to move freely inside 

 the old, and can easily turn end for end. It has been seen in many species to finally 

 quit the old skin by simply walking out, the skin having split in the front part of the 

 ventral side. 



Eyes. — It is recognised that the presence or absence of the eye-spots is too uncertain 

 to allow of their use as specific characters. While agreeing with this, I am inclined to 

 think that the eye-spots are as stable as in other groups of the lower Invertebrata. In 

 a species possessed of eyes, blind individuals may occur — it is a case of defective 

 development merely, — but I do not expect to find the converse, viz. species normally 

 blind, to have occasionally individuals with eyes. 



Blood. — The watery fluid filling the body cavity contains numerous large nucleated 

 corpuscles, now called fat-cells. These, commonly hyaline and colourless, may become 

 yellow, grey, or black, doubtless in relation to the activity of their functions. In some 

 species they are of a characteristic colour — golden brown in M. coronifer, paler yellow 

 in M. islandicus, reddish in an Indian species, etc. 



Stomach. — The stomach walls often present distinctive characters. They may be 

 composed of very few large cells, only 6 or 8 visible in one view, or of very numerous 

 smaller cells (M. coronifer). These cells often have contents of a characteristic colour — 

 sienna-brown in M. annulatus, umber in M. coronifer, and so on. Animals are often 

 found with the stomach of a deep blue or sometimes green colour. This colour is 

 within the cell, and independent of the stomach contents, though perhaps chemically 

 resulting from the nature of the food. It is not known whether it is an invariable 

 characteristic of certain species, but there are reasons to doubt this. M. papillifer only 

 occasionally has the blue granules in the stomach cells. Richters found the blue stomach 

 in M. islandicus, but whether constantly I do not know. In littoral collections from 

 Loch Ness examples with blue stomach are always abundant and belong to several species. 



