ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 591 



necessary to note that there is no blood-plexus, so that they are probably 

 only accessory organs of respiration. The eye is not, as has been thought, 

 formed by the union of two, but of four simple eyes arranged in cruciform 

 fashion. Though the sexes are separated the gonads are similar in position 

 and are best developed in spring and summer ; at the reproductive period 

 they attain a considerable size ; the five pairs form elongated ovoid masses 

 which float in the coelom, and are merely held in place by a vessel vi'hich 

 arises from the ventral trunk ; the ovaries are of a greenish brown and the 

 testicles of a light rosy colour. As the integument is tbin enough for 

 the gonads to be seen through it, it is easy to determine the sex of a living 

 specimen. 



Nephridia of Lanice conchilega.*— Mr. J. T. Cunningham gives an 

 account of the nephridia of Lanice conchilega Malmgren, which, owing to 

 their coalescence, present a condition which approximates to that of the 

 excretory system of vertebrates. On dissection, four long double 

 nephridial tubes are seen projecting dorsalwards, and examination shows 

 that these tubes belong to somites 6-9. The lower parts of the efferent 

 tubes are very wide, and cannot be separated from one another. In 

 somites 10-13 there are membranous nephridial sacs, which, externally at 

 least, are inseparable from one another ; these sacs are simple, and appear 

 to be devoid of a nephrostome. When a number of horizontal longitudinal 

 sections were made, it was seen that the lower parts of the efferent limbs 

 of the four anterior normal nephridia, and the whole of the succeeding 

 nephridial sacs are in open connection, so that a wdde continuous longitu- 

 dinal tube extends from the sixth to the thirteenth somite. This is the 

 first case in which communication between successive nephridia has ever 

 been discovered in any adult invertebrate, and, though the presence of a 

 metameric series of nephrostomata in vertebrate embryos has long been 

 seen to constitute a resemblance between them and the ChaBtopoda, no 

 Chaetopod was known to resemble a vertebrate by having a number of 

 nephridia coalesced to form a continuous longitudinal tube. 



Criodrilus lacuuiD. — Dr. L. Oerley f gives an account of his morpho- 

 logical and biological observations on this incompletely known terricolous 

 Oligochfete. It is a mud-worm 4-12 cm. in length, dark-brown or greenish 

 dorsally, the body is quadrangular, and ends in a pointed yellowish, and 

 often regenerated tail. There are from 200-250 or more somites ; the four 

 rows of setee extend along the corners of the body ; the genital organs are 

 on the plan of Lumhricus, and present no peculiarities ; the spermatophores 

 are hornlike, and vary in number ; each consists of a homogeneous, hyaline, 

 mucous substance, in which a number of fine elongated filaments are 

 imbedded. The bundles of spermatozoa are massed together in a spiral 

 fashion. Nothing positive is known as to the time of sexual maturity, but 

 Dr. Oerley is inclined to place it from March to the end of May. In no 

 case did he find any trace of a clitellum, or of the so-called tubercula 

 pubertatis ; the male genital pore has a great glandular areola, and this 

 appears to replace the clitellum. The cocoons are spindle-shaped, parch- 

 ment-like structures about 5 cm. long ; they change in colour in a way 

 which reminds the author of the egg-cases of shark embryos, and, as in these, 

 it seems to be due to chemical changes. The structure of the cocoon is 

 described in detail. Criodrilus is to be found when the bottom of rivers is 

 very nitrogenous, owing to the decomposition of organic matter ; Sium 

 latifoUum appears to be its favourite plant. In the economy of nature 



* Nature, xxxvi. (1887) pp. 162-3. 



t Quart. Journ. Micr. Sci,, xxvii. (1887) pp. 551-60 (8 figs.). 



