On the Develojmient o/'Ecliinorhynchus gigas. 441 



and an interfibrillar central substance. The first grade occurs 

 frequently m the inner tentacular layer, the second in the outer 

 tentacular layer of Actinia nivea, Less., and A. efceta, and 

 almost always m the muscles of the vanes, the th'ird always 

 m the diffused annular muscle of the body- wall, and on those 

 points of It where the septa are attached, and also in the outer 

 tentacular layer of Tealia crassicornis. 



LV. — On the Development q/Echinorhynchus gigas. 

 By Prof. A. Schneider*. 

 The ova of this worm are scattered upon the ground by the 

 pigs. Here they are eaten by the larva of Melolontha vul- 

 garis, and thus arrive at their further development. The ova 

 burst in the stomach of the larva ; and the embryos contained 

 m them can then penetrate, by means of their spines, through 

 the intestine into the body-cavity of the larva ; here they be- 

 come developed, and again reach the intestine of the pig by 

 the agency of the larva. 



The larvai infested with Echinorhynchi live on until their 

 metamorphosis into cockchafers. As the thorax of the cock- 

 chafer is ^ not unfrequently eaten by man, we can understand 

 that Echinorhijnchus gigas may also get into the intestine of 

 man. It has once been found in that situation by Lambl. I 

 have never succeeded in procuring the development of the 

 e.m\)xjo^ oi Echinorhynchus gigas either in the larvae of Tene- 

 hrio molitor or in Aselhis aquaticiis. 



When the embryos have arrived at the body-cavity of the 

 larvai of Melolontha, they remain for some days unaltered and 

 capable of motion ; they then become rigid, acquire an oval 

 form, and envelope themselves in a finely cellular cyst, which 

 is formed of the connective tissue of the larva. The skin of 

 the embryo, with its circlet of spines at the anterior extremity, 

 continues at first to be the skin of the growing larva ; and it 

 is only at a later period, when the formation of the hooks 

 commences, that it is thrown off, when it forms a second 

 cystic envelope. 



The considerable size and perfect transparency of the larva 

 of Echinorhynchxis gigas permits its development to be more 

 accurately traced than in other Echinorhynchi, the develop- 

 ment of which was first investigated by Leuckart and after- 

 wards by Greef. Here only those facts can be given which 

 are intelligible without figures. 



* Translated by W. S. Dallas, F.L.S., from the ' Sitzungsbericht der 

 Oberhessiscben Gesellschaft fur Natur- und Heilkunde/ March 8, 1871. 

 Ann. & Mag. N. Hist. Ser. 4. Vol. vii. 32 



