40 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
points, T. Masoni is remarkable for the mode of arrangement of the setse 
in the posterior third of the body ; they are not arranged in couples 
as in the anterior two-thirds, but are equidistant from one another ; and 
this disposition gives the woim a striking appearance. 
B- Nemathelmintlies. 
Development and Anatomy of Gordius tolosanus."^ — Dr. 0. v. Lin- 
stow gives an account of the anatomy and development of Gordius tolosanus 
Duj. It is probable that the small embryonic larvae are encapsuled in 
the aquatic larvae of Ephemera, Corethra, Chironomus, and Tanypus, and 
that the large forms live freely in the body-cavity of terrestrial beetles, 
which fall into the water in spring, whence the Gordii again reach their 
jiroper element. The passage from one host to the other can only be 
effected in late summer when pools and ponds begin to dry up, and the 
beetles are able to get at and eat the dipterous aquatic larvae. The 
larvae return to the water in April, and at the end of June sexually 
mature examjiles are found in the water. 
In the cutis of the larva Dr. v. Linstow was unable to find the four 
layers described by Camerano, the external cuticular and the fibrillar 
layers being alone present. The muscles are all longitudinal and the 
long muscle-cells have an elongated, rod-like nucleus ; the differences 
in the arrangement of the muscles at the hinder end of the body in 
the larval males and females are pointed out. The cell-body serves 
partly as a support for the internal organs, partly as packing, and partly 
as a formative body for the testes and ovaries which are as yet un- 
developed ; the segmented arrangement of the cells is remarkable. 
Both male and female larvm present, in transverse sections, two lateral, 
symmetrical, and one asymmetrical cavity ; in the latter lies the enterou 
and at its ventral surface the nerve-cord, and the author regards it as 
the coelom. It differs in form in the two sexes. The anterior part of 
the digestive tract becomes closed in the larger larvae; the thick com- 
mencement of the oesophagus is made up of two lateral and symmetrical 
halves. The intestine has a distinct lumen ; in the male the efferent 
duets of the genital tubes open into the terminal part of the intestine, 
and in both sexes the end of the gut has a very wide lumen and very 
thick walls. The central nervous system commences just behind the 
mouth with two partly-developed swellings which are connected with a 
large nervous mass which entirely surrounds the oesophagus ; a little 
further back the organ consists of three distinctly differentiated cords 
which lie close to one another, and are supported at their base by a 
nucleated mass. The author’s account of this part of the nervous 
system differs altogether from that of M. Villot. With Camerano, the 
author denies the existence of an intermuscular or interparenchymatous 
water-vascular system, which has been described by Villot. 
In sexually mature forms, ocelli, which have been hitherto overlooked, 
were observed ; they are two small lenses surrounded by black pigment 
spheres and sejiarated from one another by 0*082 mm. The walls of 
the two spaces which lie symmetrically on the dorsal side of the coelom 
and extend through the whole length of the male, are converted into the 
* Arcli. t’. Mikr. Aiuit., xxxiv. PP* ‘21^-08 (3 pis.). 
