640 F. F. LAIDLAW. 



papillae formed by the bulging out of the epidermis occur on 

 the proboscis (fig. 5, T.), and soriie few at the hind end of the 

 body. The flattening observed at the hind end of several 

 specimens is undoubtedly connected with the mode of attach- 

 ment observed by Mr. Goodrich. 



The average thickness of the epidermis is 5 fx. No 

 cell limits can be discerned in it. In sections of specimens 

 preserved with Lang's reagent small clusters of nuclei^ four 

 or five in each cluster, are scattered at considerable inter- 

 vals through the epidermis. The outer limit of the epidermis 

 is seen as a delicate line^ which under high power resolves 

 itself into a row of exceedingly fine dots, recalling exactly 

 the appearance figured by Bohmig for Monoophorura 

 striatum, Boh. ; whilst the clusters of nuclei suggest the 

 " Tastkorperchen " of the same species (3, pi. xx, figs. 17 — 19), 

 except that there is no break in the cilia above them. In the 

 case of sections of specimens fixed with corrosive sublimate 

 and acetic acid numbers of small deeply stained rhabdites 

 are visible in the epidermis. Assuming that the ckisters of 

 nuclei referred to above are to be regarded as connected 

 with sensory organs, the question arises as to the where- 

 abouts of the true epithelial nuclei. The nuclei in the 

 clusters are the only ones occurring in the epidermis so far 

 as my sections show. 



The basal membrane is thin, about 1 fi. thick or rather 

 less. The muscle layers consist of an outer circular and an 

 inner longitudinal layer, evenly developed all over the body 

 (fig. 7, Cir., Lon.). Special sphincter muscles, derived appa- 

 I'ently from the circular layer, lie round all the three openings 

 in the body-wall (figs. 4 — 7, Sp.). But few gland-cells are 

 developed in connection with the sui-face of the body. A 

 few cells with granular deeply staining protoplasm lie here 

 and there immediately under the muscle layers of the body- 

 wall, and doubtlessly come into this category; they are 

 more numerous in the proboscis than elsewhere (fig. 5, Gl.). 



Parenchyma. — The space between the various organs of 

 the body and the body-wall is occupied by the parenchyma, 



