370 SUMMARY OF CURRENT RESEARCHES RELATING TO 



no pores could be detected in the hyaline cuticle, nor were the rod- 

 shaped or spindle-like structures which are so often to be made out 

 in the hypodermis of Annelids detected in this form. In correspond- 

 ence, possibly, with their tubicolar habit, the muscular layers are 

 not thick ; the division of the body-cavity into three longitudinal 

 chambers, owing to the development of muscular plates, such as has 

 been signalized by Claparede in various Terebellce, could not be here 

 demonstrated. 



The coelom is well developed, especially in the more anterior 

 regions, but the so-called dissepiments marking off the separate seg- 

 ments were not observed. The body-cavity is continued not only 

 into the parapodia, but also into the lobes of the head, the gills, and 

 the filiform tentacles ; with the exception of the first, the outgrowths 

 are traversed by a connective-tissue plexus. A large lacuna at the 

 base of the tentacles supplies those organs with fluid, and they then 

 become extended. The general cavity is filled with a colourless 

 fluid, which exhibits a constant lively movement, not marked by any 

 regularity in direction. A number of discoid ellijitical corpuscles, 

 which are never coloured, are always to be found in it. The liver is 

 made up of lamellee, which are set longitudinally, and it has the same 

 cylindrical epithelial cells as the oesophagus ; the muscular stomach 

 is regarded as being homologous with the similarly named organ in 

 Lumbricus ; sections made across the anterior jjortion of the intestine 

 (or " hindgut ") exhibit the presence of a number of inwardly pro- 

 jecting folds, the largest of which is to be seen on the dorsal side ; 

 these folds are richly provided with blood-vessels, and when the dorsal 

 vessel becomes smaller and divides into two, as it does in the 22iid 

 segment, the folds become proportionately smaller. The author takes 

 the same view as Claparede with regard to the tubicolar functions of 

 the salivary glands. 



The " ventral medulla " is intermediate in character between [the 

 step-ladder form, seen in Seri^ulidse and others, and the fused cord 

 found in Scoloplos, for here the two longitudinal cords are only sepa- 

 lated by a connective-tissue sheath ; in the hinder portion of the body 

 it passes into the hypodermic area. Special ganglionic enlargements 

 are not developed in each body-segment. Unlike what obtains in 

 the earthworm, but just as in the oligochaetous Enchytrasids, the 

 investing membrane consists of a homogeneous, and not striated, 

 neurilemma, but there does not appear to be any cellular structure in 

 this neurilemma. 



The most conspicuous portions of the blood-vascular system are 

 the two large dorsal and ventral vessels, and, in addition to these two, 

 there are two longitudinal vessels on either side of the body ; of 

 these the upper is more delicate than the lower. The blood is corpus- 

 culated ; the corpuscles being numerous, and of an ellij)tical form. 



The females ajipear to be more numerous than the males, and are 

 distinguished by their yellowish-green colour ; the ova are developed 

 in a tissue of the segments, which seems to be homologous to the 

 ovaries described by Grube in the TerebellidaG, The germinal 



