Studies in mammals have indicated that PHI (peptide histidine isoleucine) and VIP (vasoactive intestinal polypeptide) share a prepropeptide, and that both peptides are contained in the same neurons. The present study proposes that this relationship may not hold true in protostomian invertebrates. In the nervous system of the cockroach (Insecta, Arthropoda) and Aplysia (Gastropoda, Mollusca) dis...

The generic name Scaphella was proposed by Zenkova (1977: 81; type species S. gibbosa Zenkova, by original designation) for a new fossil ostracod genus from the Middle Silurian (Wenlockian) of the eastern slope of Middle Urals (Russian Federation). However, this name is already preoccupied by a marine gastropod molluscan generic name Scaphella Swainson (1832: pl. 87), which is in active current...

Evidence is reviewed to evaluate whether the term "brain is justified in referring to the snail's cerebral ganglion. The focus of the review is terrestrial species, with particular attention given to the genus Helix. In accordance with a standard definition of "brain, the cerebral ganglion is found to be differentiated both structurally and functionally. It receives convergent sensory inputs fr...

The freshwater snail, Bithynia tentaculata (Gastropoda: Prosobranchia), is frequently found in gravel pits and its role in the transmission of larval digeneans was assessed in one of these unstable water bodies from the Lower Thames Valley (UK) from June 1982 to December 1984. Eight species of cercarial and five species of metacercarial infections were reported from B. tentaculata, with up to 7...

Some generally accepted viewpoints on the phylogenetic relationships within the molluscan class Gastropoda are reassessed by comparing complete 18S rRNA sequences. Phylogenetic analyses were performed using the neighbor-joining and maximum parsimony methods. The previously suggested basal position of Archaeogastropoda, including Neritimorpha and Vetigastropoda, in the gastropod clade is confirm...

A new species of planorbid mollusc, Plesiophysa dolichomastix (Greek dolichos = long, mastix = flagellum), collected from Lagoa da Pedra, municipality of Santa Rosa, state of Goiás, Brazil (15 degrees 01'S, 47 degrees 13'W) is described. It is indistinguishable by the shell characters from the five congeneric species described so far: P. striata (Orbigny, 1841), P. granulata ("Shuttleworth" Sow...