EXPLANATION OF PLATES 373 



rj,ATE 14. MOKI'IIOLOGY OF THK TREPOSTOM ATA. 



l'"iiiURE 41'. — Loin/iliKlinal section of a poiiion of the tvaH nf lijillioitora (/rueilis. 

 Mature resioii nenr the surface of the zoariuiu. The granular 

 appearance of the dark hands and 1h(> ahsence of any suggestion 

 of a dujilex wall are distinctly indicated. X 287. (L"i9-7. ) 



Figure 43. — LonnitiidiiKil xrctiou in the tnatnre refiion of Aiitple.rnpora mutti- 

 spiHoxu var. 



This section shows the cingulum (c) and the indefinite character 

 of the so-called dark line. Compare with figure 48. X 287. 

 (126-2L) 



Figure ^^.-^Ballopora roinoso. iinilnre region. 



The cingulum and its relation to the diaphragms is shown. 

 The wall lamin;ip in some cases nui across the axial region of the 

 wall and in other cases are offset at the axial plane. Farther in 

 toward the axial region, this species often shows a well defined 

 dark median line in tlie wall. X 287. (128-17.) 



Figure 45. — Batostoma icincheUi, mature region. 



This is the most extreme development of the dark median zone 

 in the Integrata. Note the relation of the diaphragms to the 

 secondary thickening of the wall. X 287. (188-20.) 



Figures 46 and 47. — Sections of the wall in the mature region of tico specimens 

 of Heterotrypa prcenutia var. simplex. 



These sections show the integrate and amalgamate phases of 

 wall structure in the same species. The relation of the dia- 

 phragms to the cingulum is also well shown, x 287. (188-21; 

 198-16.) 



Figure 48. — Heterotryim prolifica, via tare region. 



The most tyiiical amalgamate structure. The median dark zone 

 is hroad, and the lamina^ pass across with a gradual curvature. 

 The whole dark region has a distinctly graiuilar appearance under 

 high magnificat ion. owing to the concentration in this region of the 

 larger wall grannies mentioned in the text. X 287. (101-20.) 



Figure 1!). — Eridotrgpa simulatri.r, mature region. 



A mcinlicr <>t' tii(> Aninlgamata with a very sliarply d<»lin(>d 

 median dark line in portions of the wall, which hecomes inter- 

 i-npted and indefinite in other portions. The wall lamina» pitch 

 very steeply away from the axial region of the wall. Compare 

 with figure 45. X 287. (129-12.) 



Figure 50. — Dil.mjiit nidciilaln. m a In re' region near the surface of the zoarium. 

 .\n extreme case of the ;inialgainn((> structure. The develop- 

 ment of (1,'irk tissue is very irregular, mikI there is no suggestion 

 of a definite median zone, nor of a duplex wall. X 287. (16(5-8.) 



XXVUI.— liLi.i,, <;i;uL. Sue. A.M., Vol. 20. U)14 



