60a MESSES. E. HERON- ALLEN AND A. EAELAND ON THE 



Gmelin's species Nautilus litims, were it not for the fact that it must lapse " for 

 uncertainty," should therefore stand sensu restricto for the long spiroline forms, and 

 the specific name cylindraceus of Lamarck might be retained to cover the shorter and 

 stouter forms, intermediate between the less elongate P. arietinus and Spengler's form, 

 i. e. the form figured by Blainville (text-fig. 44, L), and in d'Orbigny's Modele no. 24 

 (text-fig. 44, M), to which (to add to the confusion), Lamarck, as figured by Crouch * 

 (text-fig. 44, O), gave the further name Spirolina clavata, and d'Orbigny in 1846 

 (FFV. p. 137, pi. vii. figs. 7-9) called it Spirolina austriaca, which name Reuss 

 adopted in 1861-65, making it his Model no. 25 in the Catalogue (text-fig. 44, P). 



Parker and Jones in their ' Nomenclature ' f were in a sense right, therefore, in 

 saying that Nautilus lituus (Gmelin) was identical with Spirolina cylindracea 

 Lamarck (text-fig. 43, E), if they referred only to the elongate spiroline type [which 

 Lamarck should have named Spirolinites acicularis (Batsch)] and not to the Spirolina 

 cylindracea Lamarck, as figured by Blainville (text-fig. 44, L) and represented by 

 d'Orbigny's Modele no. 24 (text-fig. 44, M). We do not advocate this correction in 

 accordance with the strict rules of priority, for the reason that the specific name 

 cylindraceus has now been used by a great number of authors for nearly a hundred 

 years, and to substitute acicularis for it now, on the strength of Batsch's almost 

 unattainable work, would lead to very great confusion. 



The conclusion that Ave have arrived at, therefore, is that the shorter and stouter 

 spiroline forms must be called P. arietinus (Batsch), the name P. cylindraceus 

 (Lamarck) must be given to all very narrow and elongate forms with small spiroline 

 commencement, and the name P. lituus must lapse, Brady's specimens figured under 

 this name coming, as we shall now see, into Chapman's subgenus Monalysidium. 



Brady's identification of his specimens of P. lituus with Spengler's original figure 

 is, as we have seen, based upon the supposition that the specimens which he 

 figured were fragments of an organism of which the initial spiral was lost — an 

 inversion of Spengler's views as to the identity of his specimens with Klein's. The 

 identification is, in our opinion, untenable, regard being had to the numerous speci- 

 mens which we have seen, both at Kerimba and elsewhere, none of which has ever 

 exhibited any trace of an initial spiral portion. They are nearly always characterized 

 by a definite aperture at both ends, and present normally little, if any, variation 

 throughout the diameter of the shell. Millett, who adopts Brady's identification 

 for these forms, observes %, " although there are numerous examples of the fragile form 

 P. lituus, not one of them possesses the initial chambers." 



Chapman § has suggested a new subgenus, Monalysidium, to include " the long, 

 delicate, crozier-shaped specimens of which Nautilus lituus (Gmelin) is the type." 



* E. A. Crouch, 'An Illustrated Introduction to Lamarck's Couchology ' (London, 1827), p. 40, pi. xx. 

 fig. 8. We cannot trace that Crouch had any authority for making Lamarck responsible for this new name, 

 t P. J. & B. 1859, etc., NF. 1859, p. 481 (J.). 

 % M. 1898, etc., FM. 1898, p. 613. § C. 1899, FFA. pp. 3, 4, pi. i. figs. 5, 6. 



