THE SESSILE BARNACLES. 221 



B, auricoTTM. Hoek. 



B. ciTiatus Hoek. 



B. co'tppressm Hoek. 



Before proceeding with the descriptions of species, I may be per- 

 mitted some remarks on Balanus (pveas Lanchester/ of which I have 

 been able to examine the type material, through the conrtes}'- of 

 INIr. C. Forster Cooper, in charge of the University Museum of 

 Zoology, Cambridge. 



The t3'pe as preservpd consists of both scuta and terga of one indi- 

 vidual (pi. 47, figs. 2, 2fl, 2r?, 2fi?) and a scutum and tergum (pi. 47, 

 fig. 2^) of another. I have therefore not been able to add any- 

 thing to JNIr. Lanchester's account of the walls, basis, or internal 

 anatomy. 



The scutum has narrow, very little raised and widely spaced 

 growth ridges, much like some forms of B. mnphitrite. The articular 

 ridge is prominent and somewhat reflexed. The adductor ridge is 

 very narroAV and low, and there is a smaller ridge parallel with it, 

 nearer the articidar rib; these two ridges are connected above by a 

 semicircular ledge, bounding the flat, depressed interval between 

 them; and in suitable light they appear to form a narrow inverted 

 U. The pit for the lateral depressor muscle is small but distinct. 

 The tergum has a distinct though quite shallow depression running 

 to the spur, varying in deptli in the two individuals. The carinal 

 margin is arched, and shorter in one of the examples, and it bears 

 numerous delicate hairs. The crests are well developed. 



It will be noted from the above details, together with Mr. Lan- 

 chester's account, that this form agrees ver}' closely with Balamis 

 socialis Hoek.^ I can find no tangible differences; and unless the 

 cirri (which are not described in B. ameas) are shown to differ, I 

 Avould suggest that B. aneas be written as a synonym of B. soeialis. 



I may further remark that B. social ifi and B. aneas differ from the 

 other forms of SoUdohalanus by having very narrow, smooth radii, 

 witli steeplj^ oblique summits, whereas the other sjiecies have wide, 

 transversely grooved radii, with summits far less oblique; j'et from 

 Doctor Hoek's account of the mouth ]:)arts of B. soeialis, it appears 

 to belong with the other Solidobalani rather than with the B. ama- 

 ryllis group. 



''^Dalaniifs (rneas Lanchester, Proe. Zool. Soc, London, 1002, vol. 2, p. ,"70, pi. 34, 

 figs. 4, 46. Malay Peninsula, on the shells of Sirovihiis and Ntaica inhabited by the 

 hermit crab Par/vrus Jiessii Miors (Proc. Zool. Soc, London, 1902, vol, 2, p. 304 L Col- 

 lected by the Skeat expedition. 



- Balanvs ftocialis Hoek, CliaUcnpcr Report. Zoology, vol. 8. Report on the Cirrlpedia, 

 p. ir.O, pi. l.S, figs. 23-28 (ISS.I). Sibor/ff-Expeditie, Cirrlpedia, p. 192, pi. 18, figs. 2-12 

 (1913). Arafura Sea, type locality ; also Malay Archipelago, in 9 to more than 09 meters. 



