INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 635 



the size of tlie accessory eye. Labial appendage comparatively large, 

 distinctly notched so as to appear as if composed of two blunt lobes ; 

 hind edge of shell straight, lower edge clad thickly with fine bristles, 

 and having a spine behind. Surface of shell smooth. Postabdomen 

 broad, contracted at posterior third, beneath which occur eight double 

 teeth. A short and a long spine at the base of the caudal hooks. 

 Length, "33 mm.; height, -25 mm. Its nearest ally is Pleuroxus 

 trigonellus O. F. Miiller. 



The Cyclops, G. helgolandicus n. sp., has the front antennre of 

 fourteen segments, and reaching to the end of the first body segment 

 when laid back ; the first and eighth segments agree in length, and the 

 fourth and seventh, which also agree, are together equivalent to one 

 of these. Second pair of antenna? of four segments, the first being the 

 longest. Eye with four edges, red or red-brown. Last segment of 

 outer branch of fourth pair of feet has two spines externally, a sj^ine 

 and bristles above, and three long bristles internally. Rudimentary 

 foot consists of a broad basal joint with an external bristle, and a 

 narrow terminal joint with a spine and a long bristle. The last 

 abdominal segment is the shortest, hinder edge fringed with fine hairs ; 

 caudal fnrca four times as long as this, its latter bristle at the third 

 fifth. The ovisacs contain twelve to twenty eggs, round, projecting 

 from the body. Total length, 1-GG mm. ; without furca, 1'36 mm. 



It appears to be derived from C. pulchellus Koch, difiering from 

 it mainly in having three fewer antennal joints, in being smaller, in 

 the shortening of the basal joint of the first segment of the rudi- 

 mentary feet, and of the second outer bristle of the caudal furca ; but 

 the species are alike distinguished from all others by a fringe of fine 

 hairs on the first quarter of the furca, and by the position of the 

 lateral bristle of the same at the third fifth of its length, and some 

 other points. 



The well was closed in 1809, so that the species appear to have 

 become thus modified in the intervening period of seventy-one years. 



Vermes. 



Genital Glands and Segmfintal Organs of the Polychaeta.* — After 

 a short review of the history of our knowledge of this subject, 

 M. Cosmovici commences an account of his own investigations by a 

 detailed descrii)tion of the anatomy of Arcnicola piscnlorum. In dealing 

 with the circulatory system, he points out (1) that the branches of 

 the ventral vessel go to a gill ; (2) that they meet with a segmental 

 organ, or (3 ) that they meet with both gill and scgruental organ. 



In describing the segmental organs, ho commences by directing 

 attention, in the first place, to the structui'o which he calls the organ 

 of Bojanus. Of these there -are, in Arcnicola, six pairs, which arc 

 placed on either side of the ganglionic chain, ami in the cephalo- 

 tlioracic portion of the lateral chamlxjrs of the body. They arc not 

 fi)und anteriorly to the third or posteriorly to the eighth segment of 

 ihe body. Though very variable inform, it is iiossiblc to make out in 



» ' Arcli. Z.>ol. txp. ct gen.,' viii. (1880) p. 2:53. 



