426 NOTES AND MEMORANDA. 



in which are set a large number of nuclei, each provided with two or 

 three highly refractive nucleoli ; the apj^areut absence of this layer in 

 sections of the worm, which have been treated with acetic, osmic, or 

 chromic acid, is explained by an account of what happens in the fresh 

 creature when it is submitted to these reagents ; the protoplasm con- 

 tracts, and forms more or less oblong masses of varying size, which 

 are separated from one another, and contain two or even three nuclei. 

 In the anterior part of the buccal segment this layer is thick, but 

 Uljanin was unable to make out the separate cells. The elytra are each 

 formed of a somewhat opaque nucleated mass, which is made up of a 

 number of small, distinct cells, each provided with a large nucleus, and 

 of larger bodies, which appear to form unicellular cutaneous glands, 

 such as are so common in the integument of all Chcetopoda. True 

 cilia seem to be almost comj)leteIy absent ; the buccal segment of two 

 species is, however, provided with a ventral and a dorsal hood, the 

 edges of which are jwovided with a row of long lamella?, which on close 

 examination are seen to be made up of a number of united cilia, which 

 so far seem to be just the same as the lamellje of the Ctenophora. 



The subjacent muscular layer is arranged in two sets ; the outer, 

 in which the bands seem to be circular, is really composed of large 

 bands, separated from one another by spaces almost as large ; the 

 elements of these bauds are cylindrical, and are altogether similar to 

 those so commonly found in the Annelides. The lower layer consists 

 of longitudinal muscles, the elements of which are greatly elongated, 

 narrow at either end, and provided at one edge witli small outgrowths 

 containing a finely granular substance (cf. the " nematoid fibres " of 

 Eatzel). 



Nervous System. — Uljanin contradicts N. Wagner's description in 

 almost every point ; he asserts that what this author took for the cerebral 

 ganglionic mass, is merely the glandular portion of a retort-shaped 

 organ which lies above the oesophagus ; while he further states that 

 there is a true ganglionic chain, and not merely two flattened nerve- 

 trunks. At the end of the body of the worm there appears to be a 

 tactile organ, but the most curious portion of the sensory apparatus is 

 represented by the small rod-like bodies which ave connected with the 

 elytra ; when highly magnified, an elytron is seen to contain in its 

 tissue a number of curved filaments, the two ends of which are set 

 towards its surface ; some of these spread out into a fan-like termina- 

 tion, and others remain more compact : the filaments are very fine and 

 highly refractive, and are connected at their ends with spherical and 

 likewise highly refractive corpuscles, of two distinct sizes, and with 

 elliptical bodies of a similar character. Our author is merely content 

 with drawing attention to this apparatus, which be cannot believe to 

 be made up of spermatozoids, much as they resemble them at first 

 sight. 



Digestive Organs. — The mouth is situated at the middle of the 

 ventral surface of the buccal segment and above the ventral hood ; the 

 oesophagus is short and thick-walled ; the intestine largest more 

 anteriorly, and the anus is placed on the dorsal surface of the poste- 

 rior segment ; above the oesophagus there is an elongated organ, which 



