490 SUMMARY^ OF CURRENT RESEARCHES RELATING TO 



are parasitic in the respiratory tract of water-birds — T. sisowi sp. n. in 

 the trachea of ducks, T. sarcidiornicola (Megnin) in Sarcidior?iis melanota, 

 and two doubtful species. 



Parasites and Pearls.* — H. Ljster Jameson and W. Nicol describe 

 three new species of Gymnophallus from the Scoter duck {CEdemia 

 nigra) ^ and they also deal with G. cademise ( = Lecithodendriiim so mater ise 

 Jameson ex parte). No fewer than sixteen distinct Trematodes are 

 known from this host, and nine are recorded by the authors for the first 

 time. 



Jameson showed in 1902 that the agent in forming the pearls in the 

 common edible mussel {Mytilus edidis) is the larva of a parasitic Trema- 

 tode, which, instead of secreting a cyst of its own, as is usual with such 

 larvae, stimulates the mussel to form around it a sac of epidermal cells. 

 These cells possess the same physiological properties as the outer shell- 

 secreting epidermis, and eventually, on the death of the Trematode 

 larva, secrete conchiolin and calcareous salts, which, deposited in con- 

 centric layers around the remains of the worm, become the pearl. But 

 the life-history remains obscure. It is possible that the early stages 

 of the Mytiliis parasites occur in the cockle {Gardium edide), where 

 closely related forms certainly occur. It is possible that the adult form 

 of the 3£ytilus parasite is to be found in the Scoter, but the experiments 

 which the authors have made to test this have not yielded any conclusive 

 result. 



New Species of Monoophorum.t — P. de Beauchamp describes from 

 the salt marshes of Socoa (Basses-Pyrenees) Monoophorum graffi sp. n., 

 and communicates some details in regard to the structure of the type. 

 The pigmentation is very characteristic — two transverse reticulate bands 

 of black on the dorsal surface, anteriorly and posteriorly. More needs 

 to be known as to the reproductive system. One of the features is the 

 annular yolk-gland, which is connected, like a buckle with its pin, with 

 the unpaired ovary which descends along the dorsal surface, and leads 

 into a curious pouch lined with granular epithelium. 



Incertae Sedis. 



Development of Balanoglossus clavigerus.J — G. Stiasny has given 

 a short account of his study of the development of this species. The 

 segmentation is total and equal, quite like that of Synapta. There is a 

 circular closure of the blastopore. The trunk coelom arises from the 

 hind-gut, not at the transition area between mid-gut and hind-gut. The 

 larva develops into Tornaria millleri and passes through a Tornaria 

 krohnii stage. The collar coelom arises by a constriction from the trunk 

 coelom. After the young creature has taken to the sand the gill-clefts 

 arise as foldings of the gut. The proboscis-diverticulum of the gut 

 arises as an evagination from the oesophagus. 



* Proc. Zool. Soc, 1913, pp. 53-63 (2 figs.). 

 t Bull. Soc. Zool. France, xxxviii. (1918) pp. 159-62 (2 figs.). 

 X Resumes des Communications 9e Congres Internat. Zool. Monaco, 1913, 

 ser. 3, pp. 20-1. 



