ZOOLOGY. 709 



munis and G. pentactes — were the special subjects of Mr. Kent's obser- 

 vations thus recorded, the former sometimes attaining a length of a 

 foot and the other about half the size of the larger. The tentacles are 

 ten in number and developed as "extensively ramifying pedunculate 

 plumous or dendriform tufts stationed at equal distances arouud the 

 oral opening." These, when the animals are "on the full feed," are in 

 constant motion, "each separate dendritic plume in turn, after a brief 

 extension, being distally inverted and thrust bodily nearly to its base 

 into the cavity of the pharynx, bearing along with it such fragments 

 of sand and shelly matter as it had succeeded in laying hold of." As 

 soon as a tentacle obtains a supply, it is thrust into the mouth, and one 

 or another is always moving toward or in the mouth. 



The supply thus taken in is probably ground down by "the charac- 

 teristic teeth that arm the pharynx," and the sand-reduced remains, 

 divested of their living contents, are in time discharged by the anal 

 cavity. 



Another gentleman, from certain observations in Bermuda and 

 Jamaica, "fancied that they were catching swimming creatures," and 

 thought that his observations were supported by "a fine specimen from 

 the zoological station at Naples, which has a half-swallowed fish pro- 

 truding from its mouth." The fish in question was, however, probably 

 a Fierasfer, which is a parasite of the Holothurian, and enters and 

 departs from its cavity voluntarily. {Nature, vol. xxvii, pp. 7-8, 433, 

 508,) 



VI. WORMS. 



Nematelminths. 



A nematoid worm parasitic on the onion. — The common onion, it seems, 

 is sometimes infested with a parasite in the shape of a nematoid or 

 thread-worm. The animal has been discovered and described by J. 

 Ghatin as a new species of the genus Tylenchus. It has considerable 

 resemblance to the Anguillula of wheat. In its larval state it pene- 

 trates into the bulb and disorganizes the central tissue, converting the 

 fibro-vascular bundles into a brownish-pultaceous mass. In the course 

 of ensuing growth the sexual organs become developed and offspring 

 appear as claviform larvae. These may escape through the destruction 

 of the bulb and fall to the ground. If the earth is sufficiently damp 

 they wander about, but if it is dry they are quiescent until moisture 

 ensues. They then seek the bulbs of the onion, and those that succeed 

 complete the normal cycle of life. If the worm finds entrance into an 

 animal it is passed out with the faeces, neither becoming encysted nor 

 undergoing any further development. It is urged that the best remedy 

 against the spread of the pest is, to burn all affected onions. (Gomptes 

 Rendus Acad. 8c, Paris, vol. xcvn, pp. 1503-1505; J. B. M. S. (2), vol. 

 TV, p.' 232.) 



