REVISION OF CARCHARHINID SHARK GENERA — SPRINGER 619 



No embryos were seen; the smallest non-embryo examined was 292 

 mm. and the largest was 640 mm. 



Distribution. — Western Atlantic continental coasts from Colon, 

 Panama, to Florianopolis, Brazil. 



Relationships. — Rhizoprionodon lalandei is most closely related to 

 the cognates R. oligolinx and R. taylori. It differs from them in 

 always having well-developed upper labial furrows (always longer in 

 percent of t.l. than either of the two cognates) and a typically higher 

 tooth count. In addition, it differs from R. taylori in having a greater 

 number of precaudal vertebrae and from R. oligolinx in having more 

 enlarged hyomandibular pores. 



NoMENCLATURAL DISCUSSION. — -The tvpc material of R. lalandei 

 consists of specimens of two species, R. porosus and what is here 

 considered R. lalandei. Lectotype designation is made in the ma- 

 terial listed below. The lectotype, MNHN 945, has label data in- 

 dicating only Brazil as the locality from which it was collected and 

 DeLalande as the collector. The Brazilian type locality given by 

 Miiller and Henle (1841) is stated specifically to be Rio de Janeiro, 

 but it is not associated with any particular specimen. The Leiden 

 Museum syntj^pe mentioned by Muller and Henle also has only Brazil 

 listed on the label. 



The type material of Scoliodon intermedins consists of two specimens 

 also belonging to two species. One, 284 mm., is an R. acutus from 

 the Philippines. The other, 501 mm., belongs in the subgenus 

 Protozygaena and is labeled from the East Indies. The type de- 

 scription is based on a single specimen, obviously the larger of the 

 two, and I designate it here as lectotype (see "Material")- This 

 specimen has longer labial furrows and somewhat longer precaudal 

 centra in the posterior monospondylous region than do R. taylori 

 and R. oligolinx. Both of these characters, as well as its enlarged 

 hyomandibular pore count of 20 and possibly its precaudal vertebral 

 count (one less than for any specimen of R. oligolinx), exclude its 

 being R. oligolinx, which is the only member of the subgenus known 

 from the East Indies. Its higher precaudal vertebral count also 

 seems to exclude it from R. taylori, which is known only from 

 Australia. 



The combination of these critical characters falls in nicely with 

 those of R. lalandei. Unless there is another species of the subgenus 

 in the Pacific or the specimen is an aberrant one of either of the 

 two species known from the Pacific, it seems probable that the speci- 

 men is R. lalandei and that the locality data somehow has been 

 incorrectly recorded. 



Material.— PANAMA: Col6n, USNM 79288 (1: 510 mm.), USNM 

 79290 (1: 538), ANSP 49849 (1: ca. 410). gulf of Venezuela: 



