298 Mr. F. A. Bather on Shell-growth 



Cicada pontianalca, n. sp. 



Head and thorax above dark ochraceous. Head with the 

 front laterally striated with black ; vertex with the area of 

 the ocelli and the lateral areas black. Pronotum with two 

 short, central, black fasciae at base, which widen anteriorly to 

 behind the eyes ; the posterior margin olivaceous. Meso- 

 notum with two central obconical spots, between which is a 

 central spot widened at base and a curved spot on each lateral 

 area, all black. Abdomen above dark castaneous, shaded 

 with pitchy suffusions and sparingly and palely pilose. Body 

 beneath ochraceous ; femora and tibiffi tinged with casta- 

 neous, excluding apices of femora and bases of tibiae ; oper- 

 cula pale castaneous, the margins palely pilose. Abdomen 

 beneath dark castaneous, the margins palely pilose. Tegmina 

 and wings pale hyaline, the venation dark brownish ; tegmina 

 with the apical area shaded with bronzy reflections ; the costal 

 membrane castaneous, excepting apical half, which is black ; 

 base greenish, transverse veins at bases of second and third 

 apical areas narrowly infuscated. 



The face is somewhat flat and deeply transversely striate, 

 excepting a central, longitudinal, levigate line ; the rostrum 

 is mutilated] the opercula do not extend beyond the basal 

 abdominal segment, have their lateral margins somewhat 

 straight, their inner margins very slightly overlapping, and 

 their apices somewhat broadly rounded. 



Long. excl. tegm. 32 millim., exp. tegm. 97 millim. 



Hah. Pontianak (West Coast, Borneo). Brussels Mus. 



XXXVn. — Shell-growth in Cephalopoda [Siphonopoda). By 

 F. A. Bather, B.A., F.G.S., of the British Museum 

 (Natural History). 



Introduction. 



Up to 1886 the formation of the shell in Cephalopoda was 

 explained by a hypothesis, either of simple lime-secretion (2) 

 or of lime-deposition in cellular membranes thrown off from 

 the mantle of which they were once a constituent (1 and 3) ; in 

 that year Dr. Riefstahl proposed a hypothesis of growth by 

 intussusception (8) similar to that previously proposed by 

 Miiller for Lamellibranchs (7). Kiefstahl's conclusions, 

 based on Sepia, were extended by him through Belemnites to 



