Figure of Rotifer. 243 



bellosc Thiere, i. 2, p. 9), Avliilst by most other authors, as Van Beneden, 

 V. Carus, and 0. Schmidt, it is ranked as a TurheUarian. Such a form as 

 Macrostomum setosum (Schmarda, 1. c, p. 7, Taf. i. 15 and 15 a) is espe- 

 cially instructive as showing how direct the transition may be from the 

 ciliated integument, whence the Turbellarians take their name, to the 

 setigerous exterior of the Annelids. The Nemertina s. Ehynchocoela, 

 with which these minute worms are more or less closely allied, are by 

 almost universal consent ranked as Turbellarians, and they by their pos- 

 session of a perivisceral cavity, which is wanting in the Rhabdocoelous 

 and Dendrocoelous sub-orders, bring the entire order into still closer 

 relationship with the Annelids. 



On the other hand, the kinship of the Turbellarians with the lowest of 

 the Vermes, the Trematodes and Taeniadae, is even more obvious, and by 

 virtue of it these three orders are ordinarily classed together ; and it 

 may be sufficient here to refer to the description of the class given in the 

 Introduction, some of the chief points of resemblance specified in which 

 may be illustrated from Schmarda's work, jjp. xi., xiii., Taf. ii. 22. 



For the classification and for many points in the anatomy of the 

 Turbellarians, see Max Schultze, Arehiv. fiir Naturgeschichte, 

 1849, P- 2S0; Arehiv, fiir Anatomic und Physiolog-ie, 1H53, 

 p. 251; O. Schmidt,, Sitzung-sbricht. Akad. V^iss. Wien. xxii., 



1^57, P- 347- 

 For the anatomy of the Nemertina s. Turbellaria Rhynchocoela, see 

 Keferstein, Zeitschrift fiir Wiss. Zool., xii., 1862, p. 66. 



Figure 7. 



Gregarine (Stylorhynchus Oligacanthns), a Parasite found in the intestinal tract 

 of CaUeptenjx Virgo ; after Stein, in V. Carus' Icones Zootomicae, tab. i., fig. 3. 



This animal consists of two unequal parts, the smaller being- the 

 anterior, and armed with a coronet of spines ; the larger being the 

 posterior. It contains a large nucleus. The division between 

 the two parts of the body is formed, according to Kolliker, not 

 by an involution of the integument, but by an induration of the 

 hyaline cytoplasm or protoplasm, which, together with the nucleus 

 and the fatty granules whi(;h in all but young specimens give a 

 milky colour to these animals, make up its contents or paren- 

 chyma. Gregarinae, therefore, even when ' dieystideous,' as in this 

 case, are really unicellular organisms. There ai'e no sensory, 

 circulatory, digestive, or other specialized organs in tins animal. 



R 2 



