igog.] N. ANNANDAI.E : The Indian Cirripedia Pedunculata. 



II. Valves more or less rudimentary. Tergum much reduced. 



A. Tergum ' shaped like an axe with the shaft pointing 

 towards the carina in a slanting direction. 



a. Carinal segment of scutum triangular. Carina 



divided transversely near the base 

 a\ Carinal branch of scutum linear. Carina entire . , 



B. Tergum saddle- shaped , vertically elongate, or (occasion- 

 ally) square. 



h. Carinal segment of scutum triangular ; occludent 



segment linear or almost so . . 



b' . »Scutum consisting of three linear branches, one 



horizontal and two vertical ; tergum subtriangular but 



vertical . . 



h" . Scutum consisting of two linear branches which 



meet one another at an angle less than a right angle ; 



the lower branch passing above and almost parallel to 



the basal branch of the carina 



C. Tergum star-shaped. 



c. Scutum consisting of two linear branches meeting 

 one another at an angle, the lower branch shorter and 

 narrower than the upper 



D. Valves much reduced. Tergum absent or represented 

 by an amorphous chitinous patch. 



d. Carina forked at its base ; the basal branches 

 directed upwards in a slanting direction . . 



d' . Carina sometimes absent, its base either simple or 

 forked, the basal branched, when they are developed, 

 horizontal 



99 



D. warwickii. 

 D. grayii. 



D geryonophila. 



D. rhinoceros. 



D. sinuata. 



D. Stella. 



D. cor. 



D. angulata. 



The different species of Dichelaspis differ so much from one another as regards 

 the shape of the valves that it is not surprising that attempts have been made to 

 divide the genus. In 1869 Macdonald described D. neptuni as Paradalepas neptuni, 

 in a paper entitled "On an apparently new genus of minute parasitic Cirripedes " 

 {P.Z.S., 1869, p. 440), while in 1894 Stebbing introduced a new genus for the form 

 he called Trichelaspis forresti {Ann. Mag. Nat. Hist., xiii, p. 443). The latter was 

 believed to be distinguished from all other species of Dichelaspis by the fact that it had 

 three branches to the scutum. Gruvel, however, has since pointed out that this 

 character is not constant even in individuals of Stebbing's species; it is even more 

 marked in one of my new species, D. rhinoceros, so called from the resemblance in out- 

 line between its scutum and the top of the head and the horns of a two-horned rhino- 

 ceros. There does not seem to be any justification for the separation either of these 



1 In the var. pernuda of D. grayii the tergum is absent. This species may be recognized by the 

 great length of the caudal appendages, which are from ^ to i as long as the sixth cirri. 



