ROTATORIA OR THE UNITED STATES. 
313 
so that the species must be reunited with Diurella. Weber (1898) has given an extended 
description, supposedly of this species, under Gosse’s name Ccelopus porcellus. But rather 
curiously, his figures (pi. 20, figs. 2 and 3) do not represent this species, but afford an excellent 
picture of another species, which I have called Diurella iveberi (q.v. ) . This has but one tooth in place 
of two at the anterior margin of the lorica. Weber’s description introduces characters from both 
the species concerned. The two anterior dorsal teeth, of which he speaks (but which he does not 
figure) belong to Diurella porcellus, but the high ridge belongs to D. weberi. The fact that Weber 
had before him D. weberi, not D. porcellus , is perhaps the reason why he could not find the 
prominent substyles at the base of the toes, as represented by Plate and others, for these are much 
less prominent in the former species. 
Distribution. — This species is one of the most common amid the vegetation of swamps, lakes, 
and streams. I have recorded its presence in the following localities: Lake St. Clair; Lake Erie 
(Put- in Bay Harbor, East Harbor, Long Point, Erie Harbor, and various other parts of Lake 
Erie); Crooked Lake, Newaygo County, Mich.; Old Channel, Charlevoix, Mich.: swamp on South 
Bass Island in Lake Erie; pools at Hanover, N. H. ; Graveyard Pond, Presque Isle, near Erie, Pa.; 
Huron River at Ann Arbor, Mich. ; ditch in the tamarack swamp region near Ann Arbor, Mich. 
Other observers have recorded it in America as follows: Ohio and Minnesota (Herrick, 1885, 
as Diurella tigris)-, Shiawassee River at Corunna, Mich. (Kellicott, 1888); Sandusky Bay, Lake 
Erie (Kellicott, 1896); waters connected with the Illinois River at Havana, 111. (Hempel, 1898.) 
Also taken in many parts of Europe, some of the more characteristic localities in Europe and 
elsewhere being: Germany (Plate, 1886); common in England (Gosse. 1889); Ireland (Glasscott, 
1893: Hood, 1895); near Basel, in Switzerland (Ternetz, 1892): Finland (Levan der, 1894, as Rattulus 
tigris; Stenroos, 1898); near Khai'kow, Russia (Scorikow, 1896). 
In Natal, South Africa (Kirkman, 1901). 
7. Diurella stylata Eyfertli (1878) (pi. in, figs. 27-31). 
Synonyms: Rattulus bicornis Western (1893); Coelopus similis Wierzejski (1893) (?); Rattulus bicornis n. sp. 
Scorikow (1896); Mastigocerca birostris Minkiewicz (1900). 
Distinctive characters . — This species is to be known by the two very slender, nearly or quite 
equal spines at the dorsal edge of the anterior margin of the lorica. by the conical form, and by 
the two short, unequal toes, the longest being little more than one-third the length of the lorica. 
External features . — The body is elongated conical, the thickest portion being near the anterior 
end or somewhat back of the anterior end (pi. ill, figs. 27-30). Thence the body tapers regularly 
backward to the base of the toes. The head-sheath is set off from the remainder of the lorica by 
one or two marked constrictions. The head-sheatli falls into many folds (fig. 30), when the head 
is retracted. At the anterior margin of the head-sheath, apparently a little to the right of the 
middle line, are the two long, slender spines which form the most characteristic features of this 
animal. These spines are nearly equal in length, though in most if not all specimens the right 
one is a trifle shorter than the left — a condition not found in any other species of the Rattulidce. 
The length of the spines is usually about equal to the diameter of the lorica at its thickest point, 
though there is considerable variation. The spines are not absolutely fixed in position, but can be 
bent down over the corona for some distance when the latter is retracted. At times one of the 
spines may cross the other at its tip (fig. 28). 
Extending backward from each spine is a ridge-like thickening, the two ridges including 
between them a narrow, transversely striated area (fig. 29). The entire area seems a little 
elevated above the general surface of the lorica, the side ridges being a little more elevated than 
the part between them. 
Corona (fig. 31). — The corona, in its main features of the usual character, consists of the fol- 
lowing parts: (1) Two semicircles of large cilia raised on elevations at the sides of the head (fig. 
31 , a). In many specimens when alive there is a prominent red spot at the dorsal or inner ends of 
these elevations (fig 31, r. s.), almost as brightly red as the eye. (2) Two semicircles of cilia on 
slight elevations at the sides of the mouth (fig. 31, b). (3) A large, central dorsal, fleshy projec- 
tion (c). (4) Above this (fig. 27, e) a smaller dorsal projection. (5) Two small short lobes, 
apparently crowned with cilia, at the sides (and ventrad) of the central dorsal projection (fig. 31, d). 
