ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 77 



Fam. Loricata : Dinocharis pocillum, Salpina spp., EucTilanis dilatata, 

 E. luna, Metopidia lepadella, Stephanops lamellaris, Pom- 

 pholyx complanata, Pterodina (it is doubtful whether P. iMtina 

 and P. elliptica are really distinct from one another), Anursea 

 spp., Noteus quadricornis, Brachionus amphiceros, B. urceolaris, 

 B. haTceri, B. brevispinus, B. hidens n. sp., B. decipiens n. sp., 

 and B. pUcatilis. 

 „ Asplanchniia : Asplanchna myrmeleo. 

 In the second division of his essay the author deals in order with 

 the various organs of the body, &c. : — (i.) External integument and 

 form. Apodoides stygius appears to be the only exception to the rule 

 that there is no ecdysis during growth ; a " carapace " is not really 

 confined to the members of the division of the Loricata, for it is found 

 also in Notommata lacimdata, and in some species of Diurella ; the 

 males of the Euchlanidae are, exceptionally, provided with a cara- 

 pace, (ii.) Wheel-organ. Such rotifers as have a double circlet of cilia 

 afford other proofs of a primitive organization, and the " Archirotator " 

 must be supposed to have had a sausage-shaped body, with the hinder 

 end narrower and provided with a circlet of cilia, (iii.) Musculature. 

 Our knowledge of the muscular system is as yet confined to too small 

 a number of forms to enable us to make a comparison ; the muscles 

 do not appear to Dr. Plate, as they did to Leydig and Eckstein, to be 

 completely homogeneous, but rather to have a finely granular central 

 protoplasm, while the granules are often somewhat larger and so 

 regularly arranged as to give an appearance of transverse striation. 

 (iv.) Nervous system. The large dorsal central organ cannot be clearly 

 seen to be composed of two lateral halves ; a tuft of sensory hairs on 

 the dorsal surface (" dorsal tentacle ") is very commonly formed, and 

 in its neighbourhood the hypodermis is thickened and elevated ; this 

 is found in many females and in all the males that have been ex- 

 amined; it is sometimes paired, but otherwise is not altered in 

 character, although placed further back on the body ; other sensory 

 tufts and the eyes are next described. It is possible that the granular 

 calcareous mass which is found in the brain of some species of 

 Notommata represents an otolithic mass ; it is not known to be present 

 in the male. After a few observations on (v.) the digestive apparatus, 

 the author passes to (vi.) the excretory organ. It is recognized that 

 Leydig was justified in saying that the excretory tubes were of two 

 forms, for in some they are cylindrical and of about the same width 

 throughout, while in others they are trumpet-shaped. The contractile 

 vesicle appears to have gradually arisen by the fusion of the two 

 vessels, and in the more primitive forms we find that they are not 

 fused into a basal enlargement ; in others (e. g. Conochilus) the con- 

 tractile vesicle is formed by the direct conversion of a part of the 

 cloaca, (vii.) The cement-glands are usually paired, but when reduced 

 they may form a single organ, (viii.) The connective tissue is present 

 in the form of filaments and represents the first indications of a 

 mesenchym ; in the larger species (Asplanchna), the cells from which 

 the filaments arise exhibit amoeboid movements, and the tissue has 

 thus a contractile as well as a supporting function ; the longer bands, 



