Gatty Marine Laboratory, St. Andrews. 5 



muscles needs revision, but the general structure is in accord- 

 ance with nature. His account of the circulation in both 

 Sabellids and Serpulids is excellent. 



Viallanes * (1885) thought the skeletogenous tissue of the 

 Sabellids (e. g., Sabella flabellata) approached that of the 

 vertebrates, though Krukenberg found that chemically it 

 differed. In the tentacles (his antennae) the skeleton ( Cf tige 

 cartilagineuse ") forms a central arc enveloped in thick peri- 

 chondrium continued, from the branchial lamina, and it 

 seems to be absolutely homogeneous and transparent, though 

 composed of a single row of cells. The perichondrium he 

 compares to horn, and it and the " cartilage " have no ground- 

 or fundamental substance. This skeleton is in contact with 

 a blood-vessel which passes to the tip and is surrounded by 

 a lymphatic space, and he thought that the lymph, and. not 

 the blood, respired directly. 



Pruvot f (1885), like many others, alluded to the branchial 

 " cartilage" of the Sabellids, and described the union of the 

 dorsal and ventral longitudinal muscles to form two lar^e 

 cylindrical muscles which go to the branchiae, a fasciculus 

 passing to each filament. The anterior thoracic glands are 

 coiled or tangled (" enehevetres"), and open dorsally behind 

 the branchiae in the median line. He did not place the same 

 weight as Clapare.de did on the distinctions of this organ 

 in the Sabellids and Serpulids respectively, and they are 

 soldered in the middle line in Sabella penicillus. The 

 tentacles (his antennae) vary from the normal two to ten or 

 twelve (Sabella terebelloides, S. analis, &c). In Apomatus 

 ampul I if eras, Phil., there are three pairs, and they resemble 

 the branchial barbules, whilst in Pot.amilla reniformis two 

 pairs occur, the first being well differentiated, but the 

 second represents an intermediate structure with the 

 branchial barbules. 



Andrews % (1891) described the structure of the compound 

 eyes of annelids, his Potamilla reniformis having seven or 

 eight eyes on each branchial filament instead of the three 

 given by Malmgren ; and Sabella microphthalmia, Verrill, 

 has them on the outer side of each branchial stem, which 

 likewise has transverse bars of pigment. In Dasychone con- 

 spersa, Ehlers, the eyes also occur along the outer bases of 



* Ann. Sc. Nat. 6 ser. t. xx. pp. 1-20, 1 pi. 

 t Avchiv. Zool. Exper. 2 ser. t. iii. p. 835. 

 I Juiiru. Morphol. pp. 271-399, pi. xxi. 



