75^ SUMMARY OF CURRENT RESEARCHES RELATING TO 



thrown off, but utilized. Occasionally the pseudopodic process, character- 

 istic of the spermatide, persists in the spermatozoa. 



All nemerteans observed exhibited the same mode of spermatogenesis. 

 This mode is general and typical among animals. Sabatier's account 

 obviously does not in any way conform with the facts above summarized. 



Anatomy of Langia obockiana.* — ^Dr. L. Joubia gives an account of 

 a new species of Nemertean from Obock. When alive it is about 30 cm. 

 long, and is of a carmine colour ; along the whole length of its body there 

 extends a deep dorsal groove, bounded by two pads which are generally 

 approximated to one another, but can be separated so as to widen the groove ; 

 the floor of this groove is provided with longitudinal folds ; the hinder 

 end tapers gradually. The head is of a somewhat remarkable shape — the 

 end is a little pointed, and it then suddenly swells and becomes very wide ; 

 it is divided into four by two lateral grooves, and by a less marked ventral, 

 and a deeper dorsal groove ; it is sharply marked off from the rest of the 

 body, both by its clearer hue and by a large and wide groove which forms 

 a kind of neck. 



Wheu the grooves are studied in section they are seen to be lined by a 

 continuation of the reflected skin; at the floor the epithelium is higher, 

 and rests on a hyaline layer. Beneath this, in the midst of the plexuses 

 of subcutaneous connective tissue there are large elongated cells arranged 

 radially around the floor of the cul-de-sac ; the prolongations of these cells 

 traverse the hyaline layer and penetrate into the interior of the epithelium ; 

 these are clearly nervous, and may be regarded as ganglion cells, which are 

 connected with the nerves that arise from the brain. 



The skin presents the same histological characters as that of the 

 Nemerteans, and especially of the Schizonemertini ; and the same is true 

 of the musculature. 



The digestive apparatus is interesting, inasmuch as it is extremely 

 developed in relation to the general proportions of the animal, the lateral 

 pouches being extraordinarily exaggerated, and the true digestive tube 

 being limited to a kind of central passage which merely connects the 

 lateral pouches. The csecal pouch in front of the mouth is very large, 

 being nearly 5 mm. in length, and the mouth appears to be a hole in the 

 wall of the oesophagus, which extends above and below it. The oesophagus 

 itself is completely invested in a circular layer of muscular fibres which 

 form a kind of elastic sheath to it, and must have an action on the deglu- 

 tition of food. Two thick layers of lamellae extend into the lumen of the 

 true digestive tube and considerably diminish its capacity ; they consist 

 of a delicate layer of connective tissue covered by epithelium, which was, 

 clearly, ciliated, 



Not far from the commencement of the intestine, and behind the 

 oesophagus, there are two opposite and parallel grooves of no great length, 

 which possibly serve as gustatory organs. The proboscis was very delicate 

 in proportion to the diameter of the worm ; its orifice was not at the exact 

 anterior point of the body, but a little below it, and was so arched as to 

 reach to the median part of the cephalic region, where it was lodged in the 

 midst of a sinus. 



The circulatory apparatus of Langia ohoclciana differs only in some details 

 from that of L. formosa, lately described by M. Oudemans ; nor does the 

 nervous system differ in any important characters from that of other Schizo- 

 nemertini, as described by Prof. Hubrecht. No trace of sexual organs was 

 found in the specimens which were taken in February 1886. 



* Arch. Zopl. Exper. ot Gen., v. (1887) pp. 61-90 (2 pis). 



