Macalister — On two New Species of Pentastoina. 63 



intestine, is nearly colourless, thin-walled with slight ridges, slightly 

 dilated before its anal end, but with no accessory gland. The whole 

 canal is nearly straight, and the anus is apical. The average diameter 

 of the intestine is 0'67ra»j. In none of the specimens was it enclosed 

 in the tortuosities of the oviduct, nor of the male accessory organs, but 

 these lie on its ventral side. There is an outer connective coat feebly 

 separable, and containing a few scattered stellate connective corpuscles ; 

 then a longitudinal muscular coat of striped fibres, but I could detect 

 no trace of circular fibres, such as Dr. Harley found in P. viuUicinctuin.'^ 

 The mucous membrane has a thin structureless basement raised into the 

 ridges, and covered with the surface stratum of glandular epithelium. 

 There was no sign of a corpus adiposum in any of the specimens. 

 In all the intestinal tract was empty or nearly so. 



The body wall consisted of — 1st, an outer structureless chitinous 

 wall, which showed no traces of pore canals, nor stigmata. 2nd, a very 

 fine and irregularly distributed hypodermis, containing cells with 

 branched processes. 3rd, a thick longitudinal stratum of striped fibres ; 

 and mixed with the deeper layer of this, and within it are, at 

 the extremities, circular fibres. The body cavity within this is lined 

 by a soft reticular membrane, but I could not detect the pavement 

 epithelium within, which Harley noticed. 



The nervous system consists of a bilobed epipharyngeal nerve 

 ganglion sending down two longitudinal nerve cords parallel to the 

 digestive tubes. These seem to send off branches into the body walls, 

 supplying the muscles. I saw no trace of a hypopharyngeal ganglion, 

 nor of the double ganglion described and figured by Blanchard in 

 P. prohoscideum. There was no trace of a metameric series of gan- 

 glia. There is no heart nor circulatory system, but a milky corpuscu- 

 lated fluid lies in the perivisceral cavity. There is no respiratory 

 system, nor trace of tracheal tubes, so the breathing process is evi- 

 dently dermal in site. 



The hooks appended to the head have muscular bands inserted into 

 their basipodal processes. Each hook has also a fan-shaped depressor 

 muscle, which is only a specialized part of the longitudinal muscular 

 layer of the body wall. . Other fibres from the same source, but forming 

 with them an angle of 55°, serve for the elevation of the hooks. 



The reproductive organs are the only complex structures in these 

 animals. In the female there is a vulva situated immediately in front 

 of the anus ; sometimes these orifices are so close together, that they 

 appear to have a common integumental lip around them, but usually 

 the vulva has a slightlj'' protruding lip of its own. From this ascends a 

 slender vagina of 6-\2mm in length, ending in the slightly dilated 

 fusiform uterus, which measures 25-30mm in length, and Sfnm at its 

 widest point. This is thin-walled, and ends above in a narrow oviduct 

 which ascends at first directly nearly to the head, and there turning back- 

 ward twists on itself, forming along tortuous closely coiled tube, about 



Proceedings, Zoological Society, 1856, p. 11-3. 



