12 



larva accidentally put into its glass. It had a marked peculiarity 

 in its motion. It frequently turned four or five somersaults in 

 rapid succession, and invariably went through similar gyrations 

 on coming in contact with any object. The eye was probably 

 ruptured while moulting, as deformities of the head from this 

 source are not uncommon. I have seen a deformed Simoceph- 

 alus, in which the eye had evidently been destroyed by the same 

 cause, which had elongated and compressed the head. 



This is perhaps the species found in Lake Superior, and noted 

 by S. I Smith (Fish Commission Report, 1872-3, p. 696). 



SPECIES 2. 

 Plate II. Figs. 5-7. 



Daphnia L^vis. sp. nov. 

 Length, 2-3 mm, exclusive of spine. 



Transparent, crested, head rounded in front, not prolonged into 

 an angle. Terminal claws smooth. Abdominal processes sepa- 

 rate. Macula nigra present. 



The spine may be as long as the body in young animals, or 

 short and blunt in old individuals. The outline of the head is 

 angular in embryos and young animals, but is regularly curved 

 in adult specimens. A marked crest, more prominent in young 

 than in old animals, runs along the front and top of the head. 

 Below, the outline of the head is nearly straight, sometimes a lit- 

 tle concave in the middle, prolonged behind into a sharp rostrum, 

 whose apex lies close to the edge of the valves. The outline of 

 the valves is on the whole elliptical, nearly resembling that of 

 the preceding species. The spine, however, is attached at about 

 the middle of the distance from the dorsal to the ventral edges. 

 The spine has two rows of teeth, one above and one below. Ex- 

 ceptionally, there may be also a row on each side. The lower 

 margin has a row of short spines. The markings of the valves, 

 the antennules, antennae and post abdomen, resemble the corre- 

 sponding parts of D. pulex. There are about nine caudal 

 teeth in each row. The terminal claws are smooth. The abdom- 

 inal processes are not united. The macula nigra is small. The 



