98 GOES, RETICULAKIAN RHIZOPODA OK THE CARIBBEAN SEA. 



A second species, but rather too closely allied to farcta to claim the rank of 

 species, would be Plan, tuberosa FICHT. and MOLL., seemingly identical with Rosalina 

 ammonoides Rss., Plan, angulata v. HAGEN, Plan, coronata PARK, and JONES. Many 

 forms belonging to this group (Anornalina D'()RB.) may after a closer examination be 

 recognised as the detached form of Plan, farcta, as is also suggested by Mr. CARPENTER 

 (Introd. p. 208). Planorbulina Ariminensis D'()RB. is too closely allied both to Plan, tii- 

 berosa and farcta to be distinguished as a species. 



Plan. Ungeriana n'ORB. which cannot be distinguished from Plan. Haidingeri, and 

 oth., would be a third species. It has a more finished structure and is provided with 

 finer pore-canals. 



A fourth species is Plan, reticulata. GZJZ. 



Plan, farcta ft vulgaris does not attain any larger size either on the coralline- or 

 chalk-bottom; its pigmy form is not unfrequent. The early chambers have generally 

 a reddish or orange tint. 



Fig. 226: the developed form of Plan, farcta vulgaris; nearly of the same habitus 

 as Planorb. larvata PARK, and JONES, with a narrow mouth on each of the outer 

 chambers. 



Fig. 227: pigmy form. 



For the synonymy see under the preceding. 



Planorbulina tuberosa FICHT. and MOLL. var. Ariminensis ^ ORB. 



Tab. VII, iigg. 228233. 



It may be more consistent with natural affinity to rank this variety with Plan, 

 farcta. But if Plan, tuberosa is to comprise the principal forms of the nautiloid and 

 subnautiloid Planorbulina, this variety would be the first to take a place under this 

 species on account of its decided and completely nautiloid plan of growth. Our form 

 is often rough or wrinkled, with somewhat raised and sinuous septal lines and a trun- 

 cated or even grooved margin, the edges of which are often crenulate or spinous 

 (figg. 228230). 



Another form is smoother and has not a squared margin but is single-edged 

 (figg. 231 233). It comes near to Anomal. rotula D'OKB. 



The variety Ariminensis has generally a greater number of chambers in each con- 

 volution (7 10) than Plan, farcta. Its close affinity to this is shown by its coarse 

 pores and the yellowish or reddish tint of its early chambers. 



It is very common in the chalk-ooze, but its diameter is seldom greater than 

 0,5 mm. 





