DR. T. DAVIDSON ON EECENT BRACHIOPODA. 179 



cavity; «/>, bracliial ap[)aratiis ; c, shield ; f/y;, raised portion ot the mantle forming the wall 



of the visceral cavity; *(;/, lateral vein sinus; svm, median vein sinus. 

 Fig. 20. Portion of tlie internal surface of the shell of the same species, showing the usual imbricated 



arrangement and the internal orifices of the vertical perforations : magnified 100 diameters 



(after Carpenter). 

 Figs. 21-22. Mer/erlia truncata, var. monstmosa, Seacclii. 22. Enlarged. From the Mediterranean. 



(Davidson Collection, Geol. Dept., British jSIuseum.) 

 Figs. 23-2f). Met/erlia? WUkmoesi, Davidson. From Twofold Bay, South Australia; 'Challenger' 



Expedition (in the Zool. Dept., British Museum). 26. Interior of the dorsal valve. 



Plate XX. 



Figs. 1-8. Megcrlia sanyumea, Chemnitz, sp. 1, 2. From Honolulu, Sandwich Islands (Davidson Col- 

 lection, (Jeol. Dept., British Museum). 4—8. Different modifications in the loop according to 

 age (after E. Ueslongchamps). 4. Simplest stage. 5. Second stage. 0. A third stage. 

 7. Full-grown condition: be, running section of loop ; e, peripheral section ; i, median section; 

 p, point of attachment of recurrent lamelliB ; a, supplementary lamella. 8. Adult in profile. 



Figs. 9-11. Megerlia pulchvUa, Sowerby, sp. After figures in Tlies. Conch. ])1. lx\i. figs. lOfj-lOr. 

 Probably a variation oi Megerlia sanguineal 11. Megerlia sanguinea, \;ir. jj/ilchella, Sowerby, 

 adhering to fucus. Dredged by Mr. John Brazier from the Bottle aiul Glass Bocks, Port 

 Jackson. 10-10 6. From ofl:' Shark's Point, Port Jackson, N. S. W. (Davidson Collection, 

 Geol. Dept., British ^luseuni.) 



Figs. 12-12 6. Mrgerlia Reevei, T>a\'Khon, = Ts}ncnia Reevei, Adams. From Gotto, Japan. Probably a 

 bleached form of Megcrlia sanguinea. 



Figs. 13-18. Bonchardia rosea, Mawe, sp. From Rio de Janeiro, Brazil. 13-14. Exterior of shell. 

 15. Profile view of interior of shell. 1(5. Interior of ventral valve. 17. Interior of dorsal 

 valve. 18. Profile ^'iew of dorsal valve. (Davidson Collection, Geol. Dept., British Museum.) 



Figs. 19-23. Kraussina rwAm, Pallas, sp. 19-20. From South Africa. 21-22. Ijitcrior of dorsal valve 

 to show forked process. 23. Interior of same valve to show the small labial appendages. (All 

 in the Davidson Collection, Geol. Dept., British Museum.) 



Figs. 2 1—20. Kraussina cognata, Sowerby, sp. 24. After Sowerby's fig. in the Thcs. Conch, pi. Ixviii. 

 figs. 12, 13; from South Africa (Zool. Dept. British Museum). 25. After Keeve's fig. Couch. 

 Icon., Monogr. of Terebralula, pl. ix. fig. 38". 26. Interior of dorsal valve. 



Figs. 27-30. Kraussina cognata'^ A series of specimens dredged near the Cape of Good Hope. 29. 

 Interior of ventral valve. 30. Interior of dorsal valve. (All in the Davidson Collection, Geol. 

 Dept., British Jluseum.) 



Figs. 31, 31 ff, /;. Kraussina BeshaijesijlDavidsou. Off Cape of Good Hope. (In the Davidson Collec- 

 tion, Geol. Dept., British Museum.) 



Plate XXI. 



Figs. 1-4. Kraussina jnsum, Lamarck, sp. Specimens dredged by the 'Challenger' Expedition off the 



Cape of Good Hope. 2. In Zool. Dept., British Museum. 4. Interior of dorsal valve. 1 & 3. 



In Davidson Collection, Geol. Dept., British Museum. 

 Figs. 5, 6. Kraussina Atkinsoni, T.-Woods. From Long Bay, South Tasmania (Davidson Collection, 



Geol. Dept., British Museum). (!. Interior of dorsal valve. 

 Figs. 7-11. Kraussina {Megerlina) Lamarckiana, Da\idson. From Sydney Harbour, New South Wales 



(Davidson Collection, Geol. Dept., British Museum). 11. Interior of dorsal valve of the same 



species. 

 Figs. 12-14. Kraussina [Mega-Una) Davidsoni, Velain. From the shores of the Volcanic Island of 



St. Paul. Collected by M. Velain in 1874 (Davidson Collection, Geol. Dept., British 



Museum). 14. Interior of the dorsal valve, enlarged. 

 SECOND SERIES. — ZOOLOGY, VOL IV. 24 



