ON THK AiVATOMY OF HISTRrOBDELLA HOMARI. 358 



those of Rotifers. Unlike those of Diiiophilus, they bear 

 no solenocytes. 



(4) There is a pair of salivary glands in connection with 

 the mouth. 



(5) There are fewer teeth in the jaw-apparatus than^ 

 Foettiuger has represented. 



(6) The ventral nerve-cord is composed of two portions, 

 which separate in the intersegmental to unite in the 

 segmental regions, in prominent ganglia. The metamerism 

 of the nervous system corresponds with that of the external 

 form. 



(7) In the male there is a complicated generative apparatus. 

 It is similar in all respects to that of the male generative 

 apparatus in Stratiodrilus. 



(8) Fertilisation takes place internally. The largest egg is 

 usually seen in the prophase stage of the first niatunition 

 division. The amphiaster and the spindle can be seen to 

 pass out through the body-wall with the cytoplasm, when the 

 egg is ruptured by pi'essure. It remains for some seconds 

 intact in the sea-water surrounded with yolk-granules. 



(9) In the equatorial plate there are eight chromosomes in 

 the first maturation division. 



(10) Histriobdella is to be placed close to Dinophilus. 

 It retains many Rotiferan features, and is more closely con- 

 nected with this group than Dinophilus. Histriobdella 

 and D i n o p h i 1 u s sho w distant relationship with Polygordius 

 and Protodrilus, but cannot be classed with them as true 

 Archiannelids. 



Literature. 



1. Van Benedeu, J. P.—" Note sin- une larve d'annelide d'une forme 



tout particuliere, rapportee avec doute anx Serpules," 'Bull. 

 Acad. Roy. Belgique,' tome xx, 2nd pte., 1853, j). ti9. 



2. " Histoire naturelle d'un animal nonveau, desic^ne sous le 



nom d'Histriobdella," 'Bull. Acad. Roy. de Belgique,' 2nd 

 serie, tome v, 1858, p. 270. 



