1 
(oe) 
se 30 [Morse. 
above mentioned, and states that the species has been defined by 
Prof. Dunker as D. radiata. 
The Brachiopods possess other affinities to Rotifera, beside the resemblances 
between the embryos pointed out above. We give hére a definition of the 
Rotifera condensed from Rolleston’s Forms of Animal Life, p. cxxxviii, Class 
Rotifera, inserting in italics those portions in which some agreement may be 
claimed. 
“Vermes with a retractile ciliated disk at the anterior extremity of their bodies. 
(To be compared to retractile cirri in young Discina.) Usually plainly annu- 
lated externally, never divided internally by transverse septa. (Except Lingula.) 
In most Rotifera entire body divisible into a‘ body’ proper, and a tail, anterior to 
which the digestive and reproductive viscera with their ducts are situated. The 
body can often be seen when chitinization has not advanced so far as to form a 
carapace, not only to be distinctly annulated, but to possess circular and longi- 
tudinal muscles in its walls. Cilia are never found on the external surface of the 
body, except upon the cephalic organ. 
The chitinous surface of the integument may develope setiform outgrowths of 
various shapes, or the animals may secrete or agglutinace a tube for the lodgement 
of their bodies. The tail is usually annulated when its integument is soft, (quite 
marked in Lingula pyramidata) or segmented when it is indurated. 
(The paired claw-like processes is unlike anything found in Brachiopods. 
The anus is on the back and not on the side as in Brachiopods. The differ- 
ences between the sexes is unlike the Brachiopods, though the ccecal stomach 
as in Ascomorpha, Notommata and Asplanchnia finds a parallel in the ccecal 
stomach of many Brachiopods. The jaws and gizzard are again different from 
what has yet been observed in Brachiopods.) Two or more cecal appendages 
are affixed to the commencement of the stomach, which, as also the intestine, is 
clothed with cilia. (See Morse, ‘‘ Early Stages of Terebratulina,’’ and since ob- 
served in young Rhynchonella and Discina). The Rotifera have no heart. The 
periviseral cavity contains a corpusculated fluid. No specialized breathing organs, 
(save the curious ampufle on the pallial membrane of Lingula.) The water vas- 
cular system has five ciliated infundibuliform orifices, (to be compared with the 
segmental ergans in Worms and Brachiopods). The reproduction in Rotifera 
by means of winter eggs possibly finds a parallel in the statoblasts of Polyzoa.”’ 
Features of dissolution. 
Believing the Brachiopods to be true worms, every feature of rela- 
tion, no matter how trivial, becomes important in these comparisons. 
The mere fact of Lingula pyramidata agglutinating a sand tube is of 
small moment in itself, since such a feature might of course be a 
matter of secondary acquisition. The unquestionable fact how- 
ever, that many groups of worms are notable tube builders, and this 
peculiarity is almost entirely confined to the worms, the feature of 
tube building in Lingula becomes a matter of importance in these 
