DRS. CARPENTER AND CLAPAREDE ON TOxMOPTERIS ONISCIFORMIS. 63 



" rosettenformiges Organ" which was noticed by Leackart and Pageustecher upon the two 

 first pairs of appendages of their T. quadricomis, and which is affirmed by them to be 

 entirely wanting in T. onlsciformis. This is alike remarkable for its form (fig. 9), which 

 somewhat resembles that of a melon, and for its colour, which, being a bright sulphur- 

 yellow, distinguishes it from the coloured spots noticed in the former memoir, these 

 being of a reddish orange. In the very young specimen already adverted to, these organs 

 presented themselves at the bases of the pinnulaj (tig. 14. c, d) of the two most developed 

 pairs of members. Of their nature and purpose we have not been able to form even a 

 probable guess. 



It is in regard to the caudal prolonffation of the body, and the organs which it contains, 

 that we have the most novel and important information to offer. We can now state with 

 certainty that the large specimen represented in Plate LXII. figs. 6 & 7 (vol. xxii.) was a 

 male,— the eight pairs of ovoidal bodies from which the rudimentary pinnules appeared to 

 spring being really the testes, which occupy the parts of the perivisceral cavity that are 

 prolonged into the short lateral appendages whereon these pinnules are really borne. Each 

 testis (PL VII. fig. 2. a, a) is an undivided sac, whose cavity, when the organ has attained 

 its maturity, is almost entirely filled with a mass of spermatozoa. The individual parts 

 of this mass are in continual movement upon each other, their motion being kept up 

 chiefly, if not entirely, by the action of the cilia clothing that part of the inner wall of the 

 testis which is near its external orifice. Each testis (fig. 3) can discharge its contents, 

 either externally through an orifice («) in the wall of the lateral appendage within which 

 it is lodged, or internally through another orifice {b) into the perivisceral cavity. That 

 the external orifice is distinct from tliat of the larger, ridged rosette (c) of the cUiated 

 canal, we feel om'selves able to affirm -wdth certainty ; but ^ve are not ec^ually sure of its 

 distinctness from that of the smaller rosette in its neighbourhood. The internal orifice, 

 by which the spermatozoa escape into the general cavity of the body, can only be seen 

 occasionally ; and we are disposed to think that it is formed only when the contents of the 

 testis are fuUy matured. Whenever we caused these to be discharged by pressure, it was 

 through the external orifice that they escaped. 



The spermatozoa of Tomopteris (fig. 4), which we had abundant opportunities of ob- 

 serving, are peculiar in having two flagella — a feature which, although general among 

 the antherozoids of the Algae, is very rare (if not unique) among the spermatozoa of ani- 

 mals *, — and also in being able to move in either direction with apparently equal facility. 



It will presently appear that the testes occupy exactly the same place in the lateral 

 appendages of the caudal prolongation as the ovaria do in those of the body generally, — 

 the chief difference in their apparent positions arising from the smaller size of the lateral 

 appendages in the former region, and from the more complete occupation of the cavity of 

 these appendages by the oval sacs of the testis. 



* In his 'Naturalist's Rambles on the Devonshire Coast,' Mr. Gosse mentions (p. 213) that he witnessed the 

 exit from the mouth of Pedicellina BeJgica of numerous minute pear-shaped bodies, each having " a little tubercle at 

 its larger end, around which are set a few (about four or five) long ciha or setse, twice or thrice as long as the body. 

 These are not used for vibratile action, but as oars slowly waved through the waters." Although these are termed 

 " germs " by JNIr. Gosse, yet it seems to us probable that they were multiflagellate spermatozoa. 



